Are earbuds accepted in competitive play?
In APA, I believe the National Rule is they are not allowed. However, its always best to check your local Bylaws to see what is allowed. For instance, in our LO's territory, earbuds are permitted during regular league play, but I believe that they are not allowed during any High Level Tournaments. The territory where you play may have such a rule in place, as well. Or something completely different.
It's a good idea to be familiar with the Bylaws locally for many reasons. You can always ask your LO, but that person may not always be available, too. They should be available in the app (they are on mine), under your local territory section.
I wish you luck in getting a handle on it. I've been playing APA for about 14-15 years now, and I still have to fight nerves and anxiety at times, too. If I can get out of my own head, I do OK.