What specs do I need to look at when buying a compressor?

Mine has one of the biggest aquarium pumps and I get a whole lot of air assist flow from the air assist nozzle. Plenty.

I used to think you still needed somewhat more pressure, but I no longer believe that. This is a lot.

I’m really happy that you just turn it on and have pressure. No delay in building pressure, no cycling, no condensation in the tank and worries about water separation. Much less power and quieter.