You are correct, they have developed Proton [1] which is based on Wine.

[1] https://github.com/ValveSoftware/Proton

But it's not automatically. I think the developer has to enable that. Probably because the developer is still intended (or wants) to verify that it really works properly in Proton.

Or not sure. But I have not found a way to run arbitrary Windows Steam games on Linux with Proton. Not sure how I would do that.

Yes, you can force it on all games if you want. I'm currently playing many games on the latest version of Proton.

It might be named a bit confusingly though, I'm at work and don't remember exactly but it might be worded something like "Override proton version for all games" which also enables it for games not explicitly marked as compatible.

I thought if you enabled the beta version, you could try any Windows game using Proton.

I tried Proton a while back. My experience was hit and miss with my particular collection.

have you managed to get it working on proton?

It can actually load arbitrary games with a port of Wine https://github.com/ValveSoftware/Proton/

Some games run better on wine than on their native platforms.