Just thinking out loud here, pondering what I’ve read in this discussion over the last few days.
If I’m understanding correctly, a problem with using FST is that you have to make your source code public under GPL - do I have that right?
What if you wrote a plugin (VST3) that could host (wrap) a single VST2 plugin, using FST headers?
You could conceivably write this within JUCE, using FST headers (assuming they work as well as Steinberg’s) so that this plugin could scan for all VST2 plugins, and select one to load, making it easy for the user.
You could then publish the source code for this wrapper under GPL to comply with FST license.
Could you then use and distribute this plugin with your host, without releasing the rest of your source code?