[Canon Print Studio Pro]

I too print to a Canon PRO-100 and have enjoyed the Canon Print Studio Pro plugin for its convenience. Just unfortunate that neither Canon or Affinity wants to emulate PSP for printing from AP. However, I have found that if you install the Canon driver, you can do nearly everything that PSP offers. To use ICC profiles, first of all go to Settings (for the driver), then go to the Main tab while in the Canon driver as you're setting up to print. In the middle of the Main panel you will see the Color Intensity box. Two options there, select Manual, that opens a subpanel, at the top you will see a Matching tab. Click that, choose ICC Profile Matching, which opens up all the paper profiles you have installed, including the Canon papers.

Having seriously considered all things and using the above steps, I have printed from Affinity Photo using ICC profiles. On the Main panel is also an option to select and print Pattern prints, which gives you a chance to run a test sheet so you can fine tune your setup. The only hangup I can see at this point is that the Affinity part of the Print setup offers only a Fit type/Size (percentage) option if you are needing to change the image size on the paper size you are printing to, (i.e. 5x7 image on a 8x10.) If Affinity or someone has figured this out, would appreciate the feedback.