I shouldn't have defended the API or age rating solution. It's just a trap in hindsight. That kind of solution must be rejected altogether even if it's the OS checking the app/website's age rating header, because we'd be giving the OS oligopoly (Apple, Google, Microsoft) way too much leverage, and in the long term they're going to make it so that you can only run their approved apps because unapproved apps didn't implement their age rating API. And there is no competing OS to fix that situation if those same companies keep the bootloader on their hardware locked. That still puts authority over children in the hands of governments and corporations rather than parents.
I stand by my original comment. No new laws are needed. All of the features outlined in 1), 2), and 3) should be user-controlled, and there's no need to send info over the air.
You can still get hardware that you can install your own OS on. But you have to be deliberate about picking it out before a purchase, rather than hoping to unlock a random carrier phone down the line. For example my phone is a Pixel running Graphene. It has a locked down bootloader that could only be unlocked with the online consent of Google. While this most certainly chafes me (and if I could snap my fingers and make such schemes blink out of existence I would), I do have to admit that it really isn't that debilitating.
The unlocking process zaps the userdata partition. This security model would totally suffice for locking down a child's phone. If the child zaps their phone and erases everything on it, then the parent can handle that out of band.
For the general problem, I would say that there has been a longstanding market failure here, in that parental control software isn't widespread or straightforwardly usable across different websites. Your 3 points don't really address that. (2) has been doable on standard desktops forever, and (3) just pushes mobile devices back towards the capability of desktops (which on its own is laudable!). But standard desktops have had these capabilities for decades and still haven't evolved the kind of straightforward parental controls that most parents are demanding.
I don't think it's a market failure. The reality that password-gating software installation at the OS level can be done on most desktops but not most phones is the opposite sign of a market failure. Mobile OSes have increasingly stripped down capabilities in recent years precisely because of anti-competitive practices. The reason standard desktops have not evolved even better parental control features is not because they're not doing better than phones under a free market. They are already doing better in spite of the fact that most kids use desktops a lot less than they use phones. It's just that the absolute level of demand for parental control features has been low until recent years, and even this recent wave of demand is somewhat manufactured.
You're focused on "password gating" for installing apps, but the largest subject here is websites. (also a nit: very few Linux systems are set up with noexec on home directories, I know "portable apps" exist for Windows, and I assume MacOS has similar dynamics)
> the absolute level of demand for parental control features has been low until recent years, and even this recent wave of demand is somewhat manufactured.
I don't agree with this. I think the demand has always been there and has been sort of discarded. I've personally done some of that discarding, in my younger days when the worry was of violent content but still on desktop/laptop computers where use was generally socially legible to parents. But these days we're dealing with pocket-sized devices that are no longer socially legible, plus malevolent commercial interests drawing kids in to get them hooked on dopamine drip loops.
But you seem to think the problem is solved, so tell me: what exactly are parents supposed to do here? I'm a new parent, we're still at the stage of watch videos with mama/dada, and play with the calculator app. The next step is probably curated sources of content/apps with general web browsing locked down (including self-curated things like perhaps a local copy of wikipedia). But then after that? What's the next level of expanding their scope look like, without them being subject to attack by corpos showing them ads/social media/weird slop shit/etc? Especially if they are going to have a SIM card such that I can't just filter most of this at the network level.
I haven't researched it all, and I'm sure there are some solutions. But I'm also more capable of seeking out bespoke solutions and actively choosing to use one, as opposed to the average person who wants things to "just work" and isn't going to delve too hard. Can't we agree that the pressure for this shitty legislation is coming from somewhere beyond merely Faceboot's money?
Ok, I'll give you my two cents, but you'll have to fill in the details on your own.
After curated local content, you could get an old desktop (and later a laptop too) and install a Linux distro of your choice on it, something reasonably modern. Put Minecraft on it, and show your child how to start a singleplayer world. Show them how to use the web browser, and add a curated list of sites in the bookmarks. Leave them to figure out the rest on their own. Withhold the sudo and BIOS passwords at the beginning, but give them the passwords when they're ready. I think for the sudo password, it's when they try to host their own Minecraft server for the first time, and BIOS password when they explicitly ask you for it (though these may never happen, depends on the kid, so set your own milestones). Configure the OS and programs as you see fit early on, but don't make changes secretly after they've had the computer for a few months. Block unwanted sites and limit access times with your WiFi router or OS firewall as you see fit. Eventually, they'll figure out how to get around or tear down the barriers you put up, and that's fine, just pretend you don't know or give them a vague hint if they do something too egregious like stealing the neighbor's WiFi. Gradually loosen your control as they get older. And if something breaks, let them watch how you fix it.
Don't give them a phone. Or even if you do, strip it down so that it can only be used for calls, but you can add apps over time. Don't buy them mobile data. Let them buy their own phone and mobile data when they're old enough to earn the money, and that's when your digital supervision ends.
Regarding a solution that "just works": when your child goes out to play, you're the guide that protects them and shows them around town. You know the roads, buildings, people and rules better than they do. There aren't any solutions that "just work" which exempt you from your job as a guide. Well, there are, but that just means someone else is watching your child for you. I think digital parenting is similar in this regard. Parents needs to understand the digital landscape well enough to guide and advise their kids. Solutions which don't strip away parental rights and responsibilities will require some effort to use.
I stand by my original comment. No new laws are needed. All of the features outlined in 1), 2), and 3) should be user-controlled, and there's no need to send info over the air.