Yep, it’s official, they managed to keep their projected release date 
Debian -- News -- Debian 11 "bullseye" released
But Raspbian Bullseye isn’t officially out yet – Debian Bullseye Officially released yesterday 8-14-2021 - Raspberry Pi Forums
But their repos are up, and have all the packages Volumio needs…
volumio@den:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Raspbian
Description: Raspbian GNU/Linux 11 (bullseye)
Release: 11
Codename: bullseye