Another vote for image trace. That's pretty much the only reason I use Adobe CS6 Illustrator which is going bye bye in macOS Catalina with no 32 bit app support. I don't own Affinity Designer. I do own Affinity Photo which I like and seems good enough replacement for me for Adobe Photoshop. I was looking to see if Affinity Designer could do image trace and replace Illustrator which is how I ended up on this forum.
I'm primarily a videographer. I use image trace to vectorize artwork such as posters etc to blow up portions and rearrange for 9;16 aspect ratio for HD video. I looked into Potrace and was just confused.