I don't get why. Aren't you and CDPR using Vulkan rather than DirectX by now ? If a small studio like Wube can afford to develop for Windows, Linux and even Mac, why can't you??
Anything I say to this is speculation, but making an engine like Snowdrop is a very-many year effort and usually quite tailored.
PS4 (OpenGL) is possible because there are shims provided by Sony which make OpenGL have similar behaviours to DX11.
Smaller studios don't have a legacy, usually they're highly targeted or they're using an engine provided by someone who can produce builds on multiple platforms.
Engines are simultaneously the most liberating and the most restricting thing in game development.
Obviously the Engine was ported to Linux to support Stadia, which is where the major investment would have been if we ever saw a Linux release of that particular game. Since that's done the only conclusion I can come to is financial back-pressure (PC sales are honestly not worth the headache, cheating, piracy, support issues; but are still provided, Linux support would likely be many times that effort again), and there's also Ubisofts platform distribution systems (which is intermixed with entitlement and authentication systems) and does not provide linux support.
In all, it makes me sad, because I'm a linux enthusiast and adamantly refuse to use Windows. But I've seen how the sausage is made and I have high sympathy for people making games.
