Based on firebase serve is serving http1.1 not http2:

It would be a superstatic thing. If it were updated to do http2, firebase-tools would pick up that fix. I'm not sure off-hand how difficult it would be, but my guess is that it may be pretty straight forward...

Having HTTP/2 in Firebase hosting simulation would allow me to better use Lighthouse for performance evaluation, locally. I target HTTP/2 loading patterns and now need to deploy, in order to see the characteristics.

Just trying to be the messenger here, since I noticed no issue about this existed on Superstatic side.