I do lots of testing of apps in real phones, not emulators.
The thing is that the phones must be connected to the PC all day. Because of this, phones battery get swollen and I have to buy phones regularly.
Do you know any android phone which can be connected and on all day all week without getting swollen after a time?
Must be real phones, emulators are descarted.
You could try the OnePlus 12R. The marketing claims 80% peak capacity after 4 years. But, I would instead buy a smart plug which only turns on for two hours every 12 or 24 hours. That way you only do one possible charge every day. Plus, use any limit battery charge function present on the phone(samsung, OnePlus, realme, vivo, etc)