Helldivers 2 works on linux

You can just put a blank file in the Templates directory then it shows up in the right click menu. At least it does that on PopOS

After switching about 3 years ago, I tried running photoshop through wine. It was a little glitchy visually (I hear it's ok nowadays though) so I tried gimp and just couldn't get used to it. I tried krita and its perfect for what I use it for, very easy to use coming from photoshop. I'm not sure about actions as I don't think I used them in Photoshop but it has plugins so you might be able to find something to replace what you used before

Not always true unfortunately. iirc saints row 2 was capped at 30fps on gog but not steam, and FEAR still installed the DRM software but was just patched to not use it. Don't know of any other cases like those tho

I've been using this plugin https://github.com/oh-my-fish/plugin-bang-bang fish also allows going through previous arguments with alt+up

I have an index (but not slimevr/giggletech) and didn't have issues other than the overlay was buggy when trying to view the desktop. That was a year or so ago though so may have improved.