Biscuits! This is the main thing for making homemade donuts. My grandpa used to make these with us in his deep fryer. There weren't the fancy air fryers way back when.
So how ya do it?
Take out the biscuits and make a hole in the center, so it looks like a donut. Put them in hot cooking oil and fry until a golden brown.
When you take it out, place it on a napkin to cool. Once it is slightly cooled, dip it in a sugar/cinnamon mixture.
Don't forget to fry up those holes too! Donut holes are the best!