Consume Product

At least mainstream devices with proprietary software included such as iOS, Android or Windows phone. Few devices are legit. Librem for instance has physical switches and runs GNU+Linux, Fairphone is fully customizable, you can entirely remove the camera module and you can run almost any custom ROM for better compatibility with android apps.

However, if you really wanna be safe, just get a simple button phone from Doro, turn on only when in use and speak in code words like the mafia, assume it's always listening.

What I liked about Lineage OS is that I could even get it to run on my 10+ year old Galaxy S5. So I have a degoogled phone with removable battery on android 10.

Since it's so old, I had to compile the sourcecode for that version myself on Linux though, which needs about 450(!)GB of space just to spit out the rom at the end 😂
It took me like a week to figure everything out, but was worth it.

One thing to add though about old phones, it could be a bit tricky to find a good battery. I bought like 3 batteries thinking the phone had an issue, until I figured out it's because even "new" batteries have been sitting on shelves for years at this point.
Finally bought an extended battery with a larger case for the phone, which automatically is younger since it's an aftermarket part, and it works fine.