The anti-glare is definitely worth it and it’s also very noticeable outside. The other option is that you could just upgrade the screen from ifixit if you’re also going to be upgrading your storage anyways.
All versions of the deck allow you to upgrade the SSD. There’s actually a lot more vendors selling 2230 nvme drives now. I’d recommend staying away from SABRENT Rocket since their support is nonexistent and they also have a high failure rate. The Corsair MP600 mini and Micron 2400 is a better option.
How finicky is installing custom roms on refurbished Samsung phones or android phones in general usually?
I usually avoid refurbished phones even though the flagships offer better performance and value compared to buying the midrange and budget phones but the lack of software updates are something I’m concerned about. That said, if there was a more clear recommended OS to install I’d be willing to give it a try.