2G and 3G networks are already being dismantled, if not already gone, in several parts of the world. Even if you do want to stick to those devices out of principle, you often can't, or if you can, only for maybe 5 more years.

You can still buy equivalent dumb phones, but they aren't any more open than the rest of the rabble.

Laptops are a different story, although I believe part of that battle was already lost when the Intel SSM and AMD equivalent came around. We'll see how things go when banks start to require you to enable (In)Secure Boot just to be able to log in through a browser on a PC.