I've installed multiple custom roms on 2 phones, and nothing happened. You have to know what you're doing though. I take no responsibility if you brick your phone.
The Pixel 3a has unlimited "high quality photo storage" which means, the photos are not stored in full quality, but close enough that you won't notice the difference. The exception to that is video, though. Every Android phone has that anyway, of the...
A Pixel 2 XL. Great camera, great battery life, good call quality, processor, waterproof, gets security updates every month, quite loud speakers, looks nice, and is a pretty good phone overall.
Where RCS is really useful, is with buisness. With RCS, you can even order some products, without leaving the messages app. Other companies will be able to show more info. For example, expedia will show confirmation details, a picture of your hotel, ...
