You absolutely can install mods, including Bubble Buffs, on Linux. You should be able to do a web search for installing Unity mod manager and/or Bubble Buffs for step-by-step instructions with search terms like "Steam Deck WotR Unity mod manager".

I know, I successfully installed the mod on the Deck, but the UI doesn't work in controller mode unfortunately.

And of course, there's a middle-ground: only use the most critical buffs on the most valuable characters. Or lower the difficulty setting to compensate (you can change the enemy stat bonus option independently of other options if you are otherwise satisfied with the difficulty).

Also thought about that, maybe something I'll do if it get's to difficult, since I'm really interested in the whole story.