The beta update is available to Pixel phones starting from the 5a and the full release notes are here: https://developer.android.com/about/versions/14/release-notes
MishaalRahman also did a detailed write-up in his thread here: https://nitter.net/MishaalRahman/status/1724888813653106952
What stands out is the single-app recording and screencasting, as you can now limit what’s being recorded or cast to a single app instead of the whole screen.
The detailed write-up was just that. Very good.
Looking forward to it going gold (do people still say that?!)