considering the 8t or 9?

my boyfriend is looking to get a new phone, he's upgrading from a very old iphone 6s+ that's finally giving out. i've been researching for him and the oneplus 8t or oneplus 9 seem to be a good, well priced options!

are there any issues with either phone that we should know about? hardware issues or otherwise.

i've heard the sd 888 has bad overheating issues, is that the case? he's not a super heavy mobile gamer but when he does get a better phone that might change lol. (currently he pretty much only plays pokemon go)

is there a way for him to transfer all his pictures directly? or does he have to do the ol' 'load into pc, download onto new phone' trick?

i would love to hear anyone's opinions on either phone if they have them :) thank you in advance!!