Here’s the main one I used to get started.

udemy.com/…/101Yfa3@8XPxXbG1DlivBLYGDQBz4q_2ELh5R…

I’ve started one on creating abstract art in Affinity that seems pretty good and I have a few others in my learning queue from him on specific parts of affinity that look really good but I haven’t done yet.

Him and Lindsey Marsh have a bunch of content out there on the whole suite. I took Lindsey’s course on graphic design theory that was pretty good but that course used adobe so i used it more for general concepts. I think either of them would be a good place to start.