For seniors, you might check out the Jitterbug smartphones. It's Android with a custom launcher, and from memory, piggybacking on the Verizon network.
Thankfully I was able to copy off the pictures, and I bought her a Pixel 4a, installed a tempered glass screen protector and thin/minimal TPU case, went through the settings with her, and even showed her screenshots of more user-friendly third party launchers. She opted to keep the default launcher, and it's been smooth sailing since. (I also installed Firefox and uBlock Origin on it.)