@downey The only real challenge was with #EFI, and I may have brought that on myself by trying to do the whole thing with Secure Boot enabled for Grub and Debian. I eventually got rEFInd working and went "it's working, so I'm not touching Secure Boot again!"
Really didn't have any other issues. I used the Debian "firmware inclusive" installer and then added the linux-surface kernel post-install but that was all pretty easy.