I believe you will have to wait for Darktable 4.6.1 to be released It says 17 February 2024 so should be along soon.
https://github.com/darktable-org/darktable/milestone/32 Bugfix: Make darktable 4.6 supporting GIMP
When working it will show automatically. If you have more than one RAW importer, Rawtherapee or Nufraw then have to select one.
From memory it goes, select file in Gimp, it opens it in Darktable, do your tweaking, close Darktable and it sends the opened file back to Gimp.
https://github.com/darktable-org/darktable/milestone/32 Bugfix: Make darktable 4.6 supporting GIMP
When working it will show automatically. If you have more than one RAW importer, Rawtherapee or Nufraw then have to select one.
From memory it goes, select file in Gimp, it opens it in Darktable, do your tweaking, close Darktable and it sends the opened file back to Gimp.