I think you are missing a lot of patreons and supporters by not including an export option for popular game engines like Unity or Godot. If you do like dragon bones or spine I bet the popularity of using Synfig will increase very fast. I think by now you should get the idea that game developers are highest in numbers for using this kind of software and hence most major animation software developers include support for game engines like this. If I was you I would make the export option with JSON data, texture png and skeleton data. Anyways if you make these changes, I think your business model will flourish more.
I encourage you to have direct export options for game engines like this or atleast make a plug-in for it which is easy to use.
Thanks for considering and your time.
Your new user