For years: "This will probably be part of the upcoming Gnome 46" [1], "46.0 2024-03-20" [2].
Funnily enough, this feature seems to have been released less than 6 months ago. :)
[1] https://www.reddit.com/r/gnome/comments/1asa3u0/comment/kqow...
[2] https://release.gnome.org/calendar/