I generally switch between Sony Xperia and the Samsung A series, I’m currently with Sony. This is an unpopular opinion but the side fingerprint scanner really bothers me. It’s too good compared to the under display scanner and the phone keeps getting unlocked on accident when trying to look at the time or even turning off the screen. Plus I had to register 4 different fingers to cover all hand positions. It’s a good phone otherwise.
I was actually considering getting an ulefone armor at some point but the bad software stopped me. As most of your issues are with software you should probably keep away from the really cheap brands.
It does have an option to only scan after pressing the button. But it gets a bit weird if you just pressed the button to lock the screen as there seems to be a mini race condition somewhere in there.