* "internet of shitty things"
Although I prefer "Internet of un-updated linux boxes". (A thing to which I'm ashamedly a party to. I was in a startup ~5 years back where I was responsible for the backend that provided the software and OS updates (a customised ARCH Repo and pacman config) for our hardware. The startup went under, having shipped the first production run. I kept the Arch repo up on my own dime for as long as I could, but eventually the control over the domain dried up and the subdomains it relied on no longer existed... There weren't many of our devices still connecting to them that last time the log files showed connections, but I'm looking at two of them right now which I've been occasionally doing security updates to by hand. I feel bad each time I do it, knowing there's customers out there who bought our stuff who are no longer getting any updates...)
Alternatively, you could set up a bridge by hardwiring the device to a raspberry pi and then use the pi's WiFi to connect to your existing network. You then set up traffic forwarding across the NICs, man in the middle all the traffic, and only allow certain traffic in and out. This avoids the need to create a new network.
I do this for my cameras, there's too much risk associated with them phoning home to set them up any other way.
https://insinuator.net/2020/02/critical-bluetooth-vulnerabil...
There was another one regarding the wifi chip used in many popular phones a few months ago.
Not sure that follows, it seems a quite Android-centric view? (Which I guess is valid in the context of this discussion...)
Apple do a remarkably good job (in my opinion) of providing software/security updates to older iOS devices. iPhones as old as an SE or 6S are still getting current versions of iOS.
I have a _much_ harder time keeping similar aged Android devices up to date (My Galaxy S6Edge has been stuck on Android 7 forever. I'd need to root it and install a 3rd party ROM to upgrade it. I haven't done that because I use it still as a mobile app test device, and I don't personally "trust" not stock OS installations to be particularly valid test devices for work apps...)