Ok, thanks! I think this will not work then... I noticed JCH also has an option to use http/2 push though... I will check that out as well. I do miss some option you have in your plugin. So I will try to figure out what's what and how this functionality is setup in JCH optimize. Thanks for your help so far!
I'm not sure how JCH works, but my plugin keeps track of anything pushed so it isn't pushed a second time (relying on cache after the first push). The other Joomla extensions I looked at don't do that - so pushing with them takes more bandwidth than normal while mine preserves it.