Yeah, the totally managed deployment for Pages is great to get started, but not being able to run through our regular CI tool is a major bummer and has us also sticking with Worker sites.
* build the website and produce a GHA artifact packaged as a zip or somesuch;
* invoke Pages deploy hook API endpoint;
* within cloudflare pages run a (e.g. python) script to download the artifact, decompress it and place the resulting files in the correct output directory.
Ideally these kinds of gymnastics wouldn't be necessary and it would be possible to just run something like `cfpages deploy .` but it is not absolutely impossible to get something working, either.