The important metric is the flow rate is it not? With tubeless, you want to get the air in quick
Thats what the tank’s for – if you’ve got a 6 litre tank it doesn’t make a huge amount of difference whether the motor is big or small – the rapid burst of air is going to come from the tank.
Most shops will have bigger compressors because
A – 25 litre compressors are ubiquitous and cheap (and noisy and unreliable)
B – 100 litre compressor are quiet when running and are hardly ever running if all you are doing is inflating a few bike wheels
C- the want to look like they’re doing something that you can’t do at home.
If you can inflate tubeless bike tyre with a 2ltr pop bottle you can manage with a 6 litre compressor.
a 6 litre tank at compressor pressure is going to hold the equivalent of 20 to 30 litres at MTB tyre pressure so its plenty