If the author could only communicate better and bring his changes upstream..
I tried to see what do make of his first patch against Emacs 28 that bring threading to Gnus however it was quite hard to rebase/split them up as the original patch was just one big blob.
E.g. he doesn't just add threading to Gnus but also remove or rename variables, e.g. secondary select methods. He doesn't explain changes, he adds unnecessary or rude comments to the commits or code.
The issue is that the pure GTK port doesn't have those functions that are based on Xlib such as frame properties that come from X11. Some feature specific to X11 that can be implemented purely with GTK are not implemented such as outer window id's (I have a patch for that). So in theory the pure GTK windowing system could replace the GTK with X11 calls if it optionally allows the call of functions that depend on X11 if requested.
Pure GTK also allows the use of GTK input methods besides the better high dpi scaling.
It's feature complete but limited because Wayland is limited.
For example there's no way for Emacs to know which frames are currently visible.
You could check openSUSE or Arch Linux's packaging to see how you can achieve this.
I think the one of openSUSE is the most concrete as it will use the Wayland binary on Wayland and the X11 binary on X11 and so on.
Check out the spec file here:
https://build.opensuse.org/package/view_file/editors/emacs/emacs.spec?expand=1
The build process starts at the %build section.
The bookmark file contains information when it was last modified.
It did look similar like the Gnus newsrc which also mixes configuration and runtime information.
I'm talking about the Emacs internal bookmarks not browser bookmarks.
Please use a pastebin to post the backtrace.
Run thread apply all bt to get the backtrace from all threads.
Doesn't seem to work with PGTK for me.
I'm also using Gnus with IMAP directly too but connecting to a remote Dovecot on my root server. Fetching takes maybe 1 or 2 seconds at max.
I filter all my mails on my server before hand.