I registered the forums just to give my support for linux.
I own designer, Photo and Publisher.
I also bought 12 content packs from the affinity store. I dropped windows and now dont or cannot use affinity any longer.
Perhaps create a poll and reach out via newsletter to existing customers to see who would want a linux version.
I have tried crossover, and playonlinux but neither of them could run affinity. They can however run photoshop fine. I am still in favor of the newsletter polling idea to see how many existing clients would like to switch to linux. As another stated i would gladly purchase the linux version seeing as OS is not transferable.