Hi,
Unity 6 is still in beta or preview ( sounds less scary...
), I am not sure what Alex's plan are, but usually, playmaker support comes when the beta is almost over and when they just polishing off the last few bugs, right now, unity 6 is a real mess... they moved to a "F" version which means we are getting closer, we'll see.
from experience, do not use Unity 6 until it's 6.1... at least don't use for any serious projects, it's been like that for ever, it's ok to experiment with the X.0 official release, but really, no one is using it for production until .1 or .2 even ( we only use LTS versions for production really...)
Bye,
Jean