the .NET Core on Linux is different from the .NET framework being used by Windows and WINE, if I recall. And while possible, if Steven wanted to port everything to a cross-platform UI framework, it would take a lot of his time when he could just be perfecting the player as is. I would love for a Linux-native, feature-rich client like MusicBee, hell if I had the expertise I'd do it myself.
One can still dream, but if anything it might be worth more your time sending some bug reports to the WINE developers, to fix the bugs present when running MusicBee in there. The thing with open-source (and also one-man projects like MusicBee) is that you can basically talk to a human to get something fixed, almost immediately. A recent example is that
drag and drop issues on MusicBee seem to be getting/gotten fixed in the latest staging builds of WINE - so I'd say, focus on reporting bugs to WINE rather than nagging Steven to port MusicBee to cross-platform.
