TL;DR: System76's COSMIC first alpha is going to be in late May with new COSMIC desktop apps. The planned stable release will still be in late summer with POP!_OS 24.04.
I've been following this since it started like 2 years ago so it's unbelievable that an alpha is going to be upon us so soon. This is largely the most ambitious undertaking that any libre software group has taken in a long while (apart from Asahi Linux and graphics work).
Not quite, there are some big notables
If you're not convinced, see the COSMIC store (cosmic version of GNOME software and KDE Discover)
Personally I think the window titlebars look a bit jank and the light theme needs some work but it seems like development is speeding up greatly.