@kitsunyan’s API will tell you the status of what is published/deployed:
https://forum.f-droid.org/t/f-droid-now-provides-json-api
Then build.json should tell you what’s built and what build attempts failed. You’d have to read the YAML metadata file to see which updates are slated to build, e.g.
https://gitlab.com/fdroid/fdroiddata/-/raw/master/metadata/org.fdroid.fdroid.yml