Follow the example of how buying a Linux PC works. Look at popular brands where there are vibrant online communities of people neutralizing the surveillance / control bits - pulling out the 5G modems and whatnot. It's possible manufacturers will eventually arrive at using all-in-one integrated chipset where you can't just disconnect a daughterboard or scratch the appropriate traces to a radio chip, but we're so far from that.

Bad news: we're actually closer than you'd think to that, considering how many cellular modems on their own are full blown SOC stacks and how far we've gotten into the eSIM camp.