In such case the solution is to have hardware kill switches, like on my Librem 5.

That kind of phone goes so far to protect your privacy it won't even let you use it to call anyone. (https://www.techrepublic.com/article/librem-5-review-the-lin...). The real solution is regulation with lots of teeth and oversight, so we don't have to depend on flawed products that don't work.

This is an extremely old review, when the software was in beta. Phone calls are working fine for me now.

Regulations are great, but I prefer to have both kinds of defense.

That's a good sign! I'd given up all hope for the Librem and pinephone. I guess it's time to take another look...

I agree that hardware switches are ideal, but I don't see them being common since most of the folks pushing out phones want to use those devices to collect data on the people who buy them.

Why would it, though? If you're the sort who puts your phone into a faraday cage, you're not the sort who will install an app from the stores.

zero day OS-level exploit by some govt? idk.

I thought we were talking about retail stores here, not governments.

If your threat model is governmental, then that's a whole different thing entirely. You'll have to go to true extremes to even have a chance at defending against that. For instance, you shouldn't have a cell phone at all.