@gamingonlinux

I found a mod that downscales the textures and tweaks some other settings.

I can run the game at 1080p with the Deck connected to my TV and using the in-game FSR 2.0 feature it looks good.

On some planets and cities it is still around 20 FPS, but the latency is good so it's possible to play. In indoor maps I get up to 40 FPS (which the mod seems to lock to).