Not wanting to run steam is fair, but they asked about proton, not steam.
Anyway, from a quick Google, it sounds like it likely wasn’t proton complaining about a lack of SM6.6 support, but actually GoT itself. It’s up to the translation layer (in the case of proton, DXVK I believe) to report what DX features it supports, and it sounds like it was telling the game it didn’t support SM6.6 for whatever reason. Might just be a matter of playing with some of the launch params.
Not wanting to run steam is fair, but they asked about proton, not steam.
Anyway, from a quick Google, it sounds like it likely wasn’t proton complaining about a lack of SM6.6 support, but actually GoT itself. It’s up to the translation layer (in the case of proton, DXVK I believe) to report what DX features it supports, and it sounds like it was telling the game it didn’t support SM6.6 for whatever reason. Might just be a matter of playing with some of the launch params.