Upstream has just confirmed that the new WebKit API for GTK4 is final[1] so this is effectively a release candidate for WebKitGTK 2.40.0, to be released in ~10 days.
I just uploaded the packages, the GTK4 ones are in the NEW queue. Jeremy, you can start testing the reverse dependencies whenever you want. Berto [1] https://discourse.gnome.org/t/webkitgtk-for-gtk-4-is-now-api-stable/14378
