Build 20210922 is available. It includes the September 5 AOSP security fixes.
As of this release, the build includes a backported patch, originally made by @Slion for LOS 18.1, which allows one to use "Fn-Tab" and "Alt-Tab" equivalently for switching Apps (see this thread). I find that feature really useful when holding the Pro1 by the keyboard.
I have used that modified keyboard driver for weeks without issues. Still, be warned that this code has not been merged into any official LOS branch yet, and should thus be considered experimental.
Edit:
I think I should clarify: