You could get an IKEA Dirigera, but one of the upsides of Matter is that you do not need the manufacturers hub anymore. So an Apple Homepod or a Home Assistant instance with a Thread stick will do as well! (Or any other Matter hub for that matter of course)
You're looking for a Thread border gateway. Lots of stuff already has it. Someone mentioned AppleTV and HomePod mini. Newer Google Nest speakers/displays have it as well.
Personally, I pair my wifi and Thread matter devices to my Apple Home, as each Apple TV behaves as a redundant, ethernet connected gateway. I then do a secondary pairing to Home Assistant and Google Home. Local control and it works very well.
Is it absolutely necessary to have a base/gateway? This Verge article[0] seems to imply not, but it's not at all clear to me what I lose.
If I just want a smart switch that controls a smart light, can I do that without a hub? Can I use my phone to control that light/switch in a pinch? I'm not averse to spending $100 or whatever, but it's just more _stuff_ that I'd rather not think about.
It's not strictly necessary to have separate a hub/controller, no: After all, a Matter controller is just a small computer-widget that sits on a network and talks with IP packets.
A pocket supercomputer, such as an iPhone, theoretically works just as well: It's a small computer-widget that sits on a network, right? It just happens to run on batteries and be carried around in your pocket.
It's just software at that point.
At the end of the day: The Matter devices are paired with the controller, similar to how Bluetooth devices are also typically paired with a main brain-box. (Except: A Matter device can be paired with many controllers concurrently, whereas a lot of Bluetooth devices can only be paired with one at a time.)
The network connection doesn't have to be permanent: It can work when controller is present on the network, and it will [perhaps obviously] cease to work when the controller is absent.
So if Apple has software that runs within an iPhone and acts as a Matter controller, then: Sure, no additional hardware is needed to wiggle the state of a Matter light bulb using your iPhone.
(And if that kind of local control is all you ever care about for controlling stuff then... that's good enough.)
Can't Matter devices connect directly to Apple HomeKit? So if you have a HomePod (or even a MiniPod though I'm not sure) it should connect all these Ikea devices too.
I currently use Home Assistant but want to shift to something more “mass market” as I’m bored of being family tech support.