moatdd

In 2022, I'm able to copy from the drawing app of my choice (TVPaint), and then paste it into a video game sprite editor called Aseprite, and immediately cut it and then paste it into Affinity Designer. There's something that Aseprite does to the clipboard transparency when I 'bounce' it off of Aseprite that makes it compatible with Affinity Designer. Well, I guess since Aseprite has a puny memory footprint I can just leave it running in the background and bounce stuff off of it. Modern problems require modern solutions. So, try out pasting transparent objects from all your image editing programs and see if there are any that CAN paste transparent objects directly into your Affinity programs. Once you find an app that can do this, you can then use it as a "clipboard bouncing app" to tide you over until something less janky can be found.

... or you could just not bother. Being able to freely rotate the canvas is a must for people who rely on free-handed drawing workflows and there's no way I'm running a marathon of illustration with this rock in my shoe.

How about a Scrubby Rotate hotkey (similar to how you have Scrubby Zoom) Use Space & CTRL for scrubby-zoom, and Space & ALT for Scrubby-Rotate. Then, when dragging on the canvas, the initial drag-start point is used as a pivot point (or, use the center of the canvas as the rotational pivot), and then dragging around the pivot point will rotate the canvas.