I'm working with a Darq Side member right now who is using DarqUI on EQII on Steam on Linux. He is getting updates through the utility without any trouble. At this point his only unresolved issue is an error when changing color themes and fonts, but he is able to copy files manually through the OS to make theme changes.
The good news is that Microsoft says Windows 10 will be supported officially through October 2025, and they usually extend security support for a couple of years beyond an OS version's end-of-life date. So we should have plenty of time to migrate.