Your welcome! Glad you appreciated it man. I think Unmute was really cool and is open source but its deployment is a little on the more complex side of things.
One trick, even though it doesn't "lock it down" the same way, is to use a minimalist launcher. Check out OLauncher. It is a text-based launcher, it only has room for a few apps on the homepage, and it discourages fiddling with your phone.
https://github.com/tstromberg/quietude is how I manage my Pixel phone as well as my kids; I begin with “quietude.sh disable all”, but usually re-enable maps.
It takes a similar approach to the OP - changing restrictions requires a USB cable and a computer.
andoff[1] works well. I use it to lock down DNS settings to nextdns to block all the sites I want.
Then I use lockmeout[2] to lock opening andoff to change the settings.
Also there is limitphone[3], but it has less settings and is easier to uninstall than andoff, but works via the same mechanism.
I've been using a BigMe HiBreak pro and it's pretty good! I have had issues with the usb port but after removing some cruft I really like it. Easy on the eyes, full android and I can watch videos in a pinch.
I find it makes it easier to do something else with my free time.
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