If you and your grandma only rely on the computer for its web browser, then good for you. You have flexibility that is not afforded to most people. But that's not how a person's phone works; phones dig a lot deeper into one's lifestyle, intentionally so. The walled garden was constructed to keep outsiders out, but now it seems the primary purpose is keeping those inside hostage.

Plenty of things we do every day are worse for the ecosystem than killing off mosquitoes. But killing mosquitoes provides a far greater benefit.

You're not allowed to do anything on Linux unless Gnome people like it.

For reasons like these, operating systems like Windows XP or 7 are still necessary for many accessibility related needs.

Otherwise, I recommend Retroid Pocket 6 if you like Android or want to play GC/PS2/N64, or a Miyoo Mini Plus if you don't care about any of that. Neat thing about the mini plus is its 640x480 screen, so you get Genesis/Mega Drive games edge to edge 2x integer scale if configured properly. Also has OnionOS which is a pretty good custom firmware.

Other than that, lots of these things have major problems. Watch out for things like improperly calibrated joysticks (can't run in certain directions in 3D platformers, only walking speed), screen tearing, saves disappearing from the filesystem if the system shuts down improperly during gameplay, audio crackle/poor audio in general, IPS bleed around display edges, soggy dpads, face buttons too firm, etc. A lot of problems with any given device you can run into that don't fall under the usual umbrella of review metrics, so you won't know until you realize a week into owning it why something feels off about it...

Any data we make available as an open system will also be available to bad actors.