I’ve mostly been using the Google Pixelbook charger (labeled 5/9/12/15V 3A, 20V 2.25A) seems to do the trick.
I’ve also been using a LifePowr A3 battery (labeled 5/9/12/15V 3A, 20V 4A) which ran a multi hour Switch session.
I can confirm that a (5V 3A, 9V 2A) charger is refused and has no effect.
Unfortunately, it’s hard to know whether the battery is actually charging while the projector is running. The battery level in general is pretty opaque. Hoping for more details in future firmwares.
I can confirm that when the projector is fully charged (blue LED), it can run Normal off either of these power sources without depleting the projector battery. This is despite the former power source only supplying 45W max. So PicoPix Max is ok with less than 65 watts.
If the MacBook adapters don’t work, I suspect that the PicoPix Max charges at 15V, which is apparently not labelled on the Apple chargers (only 5/9/20V). I have a 20VUSB-C dock which refuses to charge PicoPix Max, as well as headphones and other smaller accessories.