Is the metro festival Luigi and toad hint arts better than coin farming

yes, but they are not allowed in runs as they are only temporary.

They're not allowed untill we know about a method to have them forever

As long as you don't close out of Odyssey, you'll have them forever, but they will disappear soon otherwise.

yeah and leaving your switch open just isn't sustainable. Comparable to using too much fuel in Formula 1

For 100%

Yes, it is better, but you still can't use it.