I need to use Microsoft Fonts since I use my Deck as a laptop replacement and I don’t know how to download/install MS Fonts (preferrably MS 10/11). I don’t have a MS image or CD to rip it from there :/
Just out of curiosity, why do you need Microsoft fonts specifically? What’s wrong with the included fonts?
To install fonts, you need to get the font files and copy them to the fonts folder located at ~/.local/share/fonts/. The .local folder in in the Deck’s home directory, but it’s hidden by default so you’ll need to turn on “show hidden files” in the file explorer menu. If the fonts folder doesn’t exist already you can create it. After the fonts files are installed to the folder, reopen your applications and the fonts should show up.
As far as getting the font files, that’s a lot harder. The AUR package people usually use to get fonts actually is downloading part of a windows installation iso and ripping the fonts from that. If you have access to any windows PC, you can copy the font files from C:\Windows\Fonts and use those.
If you have access to any Windows computer you may be able to transfer it via ssh/stfp ala filezilla or whatever your preferred program for it is.
However I did find this site: https://www.w7df.com/?m=1 from just a cursory search, however it does seem to be for W7 though I’d be surprised if there were major changes between 7 and 10 fonts.
https://wiki.archlinux.org/title/Microsoft_fonts
Steam OS is based on arch, so this should have the information you need
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.
You could install everything you need using pacman and the aur inside Distrobox. Distrobox also makes it easy to integrate in to your root system
