For now, yes. I am looking into cross-building (at least, with the assistance of the Windows Subsystem for Linux).
A bit of an update: I have a suspicion that the code that checks if the app is packaged into an msix package might be causing crashes on Proton (since it doesn't implement the code that is necessary for it). Although I reccomend building a native Linux build, I'll look into better handling this scenario for the bootstrapper.
Thank you for your response. I unfortunately had rather negative experiences in the past on Steam with maintaining both a Linux and a Windows version.
That's why I'm currently only on Windows. If it would be possible to get it running with Proton, that would be amazing. If not, that is of course no problem. :D
Greetings