That’s actually the unfortunate part because static site generators are static sites.
I emailed this feature idea to Glitch once, and the Glitch engineers replied that “they were happy someone brought this idea up, because it was something they had been discussing lately”.
Here’s what they said:
As you pointed out, we do have a strict definition of static sites right now that doesn’t include anything that needs to be built or compiled first, and we make that determination based on files present. However, we are thinking about how to support projects that result in static sites after being built. It doesn’t share the same architecture for us on the backend so it wasn’t the first step we took when launching static sites, but it’s really useful to see that users like yourself are interested in it!
If such a feature is implemented, we might be able to run frameworks like React, Vue and Angular on Glitch as static sites.