Oh dear. Evidently this answers my question about gradients.
This is a very, very badly needed tool. As a comic book artist who primarily works with flats, a dead-simple, one-click, 2 second destructive raster gradient tool that works like a brush rather than a vector object is a MUST. It is absolutely essential to my workflow, I will use this tool dozens of times during a 30-minute coloring illustration job, maybe a hundred times on a full comic book page, and if I have to struggle with the tool for even 10 seconds each time I need to use it, this easily doubles the amount of work and is an utter deal-breaker. Saving my presets as a style is a non-answer, I need to be able to change colors, angles, and transparency on the fly.
I cannot purchase this program unless and until this tool is added. Affinity is useless to me as a professional without it.