But is it “(A Steam Deck), or (a PC running in Steam desktop mode)” or is it “(A Steam Deck, or a PC) (running in Steam desktop mode)”? In any case both cases include the Steam Deck as a capable device, it would only be a matter of changing to desktop mode

My router is a bit old and its 5GHz performance seems to be rather lacking. I still think the main problem is I’m not testing with a big game. I’ll try and post later something.

According to the documentation, you should be able to https://help.steampowered.com/en/faqs/view/46BD-6BA8-B012-CE43. Unfortunately, I don’t have big enough games to test, and I think it detects that my internet bandwith is higher than the connection to the Deck

It’s probably not worth the risk implied with second hand vs the discounted new unit directly from Valve. You should lower it or just assume you’re not going to sell it

I play Lethal League Blaze (previous game from same devs) with my friends a lot, it’s super fun, check it out

SteamOS uses inmutable partitions, you can’t install things using pacman safely. For OP’s problem my first thought is using a virtual machine or a whole different OS. Maybe there are fonts in Discover/Flathub, which is what SteamOS is designed to use, but I don’t know if that could work.

OP says the kid has been “all over scratch” so we can assume they need something more