Are they pre-cooked ones (in which case you are heating and browning them) or raw (in which case you boil them first, then brown them)?
You need to know which type you have and cook accordingly.
Yes, they look raw but are already cooked. I usually brown them in a little oil for about 10 minutes...so an Actifry should do well.
Bratwurst are traditionally browned (like sausages)....bockwurst are the ones that are heated in water (like frankfurters).