So sorry, was pretty caught up with things in college so I didn't see the message earlier.
I already had this idea on maybe having a UI editor as well in a Gatsby based site to combine the power of Volto with a super-fast, light site generator like Gatsby. But having explored Gatsby a bit further I'm kinda thinking of this whole idea more involving the deployment side ie, for instance configuring Netlify or some webhook to do a re-build every time some data is submitted or so. Forgive if I'm getting the wrong idea, please do clarify if you meant something different @tisto
Also, I just went through Asko's proposal and it seems like an amazing feature to have while it would need some research and time for a good implementation.
If instant preview works out, you could serve “gatsby develop” for editors, let them see changes immediately and then add the big green button to Plone for triggering the real static site build. That would also give implicit drafting / working copy.
About the plugin detecting changes and triggering a rebuild, this project also could help.
A wee bit caught up due to things in college, but I'll try my best to be up to date and hopefully join in a scheduled call if possible.