I have the 256GB version which has regular screen. Glare hasn't bothered me inside at all in the year and a half I've owned it. However, I have not played it outside - in the shade / twilight it may be OK depending on your personal threshold. In sunlight, forget about it :)

FWIW I've added a microSD card and it's fine. Updating the internal nVME is not on my radar, because the whole point of SteamDeck, for me and my personal use, is for it to be "play and forget", as opposed to a hobby in and of itself :). YMMV :-)