Claw nails are a little more straight forward. Therefore, a local Vet's office is an option, especially if they have and are working with Avian clients. What you're really looking for is a comfort level that they have in Toweling/holding your parrots. I have seen both clippers and Dremial tool used on claw nails. Either is fine.
Beak's are a totally different thing (wow, that was insightful

). As you know, parrots use their bill to also investigate the World around them. Lots of nerves along the base of the beak structure that message. So, I am less comfortable with just any Vet (or Vet Tech) working on the Beak. With rare exception, this is Dremial tool work and the placement is very important so that the parrot's mouth (and therefore Air Sacks) are not filled with grinding dust. Lot more training than just claw nails.
Verify that your parrots do, in fact, need their beaks trimmed. Healthy, active parrots rarely need trimming. An overly sharp beak point could be blunted with a finger nail file at home. What you are looking for is: Rapid or ongoing over-growth of the upper and/or lower beak, a miss-aligned upper and/or lower, and/or a damaged section of the beak structure. Since, these are possible signs of medical or underlying medical problems, an Avian Vet is the proper direction.
Trimming claw nails at home. I recommended that every parrot owner should know how to properly maintain claw nails. It allows the owner to closely inspect the parrot's legs and claw structures, including the bottom pads. I can trim nails, but have chosen not too. As part of normal play and with my Amazon thinking we are playing count the piggies, I'm doing my inspections.
I would rather have the Vet or Vet Tech be the target of my Amazon's discord and reserve the status of saving hero for myself.

So, if you are comfortable trimming claw nails, have at it. As always assure that you have the proper chemicals available to stop a bleeder, which is more common with parrot with black (dark) nails. As you know, a little to long is much better than a little to short!