Here's one way of making bulbous nocks. At least some Turkic arrows were done like this... then the nocks can be wider than the widest part of the shaft.
https://www.youtube.com/watch?v=KHUr93JMjqI
I'm mostly thinking of barreling arrows for hopefully more spine/release forgiveness?!, and less gpp with my bow (more speed)
Urufu, I've read something like, using a thumb plane, but maybe starting past where the nock would be or stopping before the nock.. then after barreling, the nock is carved. I think I've seen pictures too..