You need to change engines, Unity will not going to be in control for long and there are better open sourced engines available to easy redo your project in a few days with C# Programming.
This by itself is not very convincing; it is like saying "Just install Gentoo, you can still play all your Windows games on it." This is more likely to take months of dedicated work, with bugs and unforeseen obstacles continuing to crop up through the life of the project. Can you speak to the ease of migration to any of these engines from firsthand experience? If so, I would like to hear the details of what was easy and what the pain points were. Just skimming the documentation for Stride and NeoAxis, I see several incompatibilities that would require significant time and effort to refactor.