It might depend on where you live and what show it is, you can call the dept. of agriculture in your area.
I spoke to the gentleman this weekend at the H.E.R.P.S. Show in Slidell, Louisiana.
He stated
NO license required, NO federal ID number, nothing except $125 for first table decreasing for multi tables. They supply electrical but good idea to bring your own extension cords to be safe you have enough. These shows sell out quick. In Louisiana & Texas there are 24 for 2023, all are
SOLD OUT, 2024
SOLD OUT, you go on a waiting list due to vendor cancellations.