regeya

There are significant differences between WSL and Wine.  The first version was, iirc, an implementation of the Linux kernel API by Microsoft.  Since Linux is open source, they could document the API and write their own; it worked well enough to run Ubuntu on it.  WSL2 is a specialized virtual machine by Microsoft that runs a modified Linux kernel  to integrate with Windows.  It's great if you're a beardy Unix person or have used the command line in Mac OS to get things done.  I know I've used it in Windows to perform command-line magic.   Tends to work faster than Cygwin and easier than rebooting just to do some Unixy command line stuff (and don't get me started on Powershell.)

Wine is a different beast entirely.  It's an implementation of Windows APIs, written from scratch, merged from multiple projects over the years.  Windows is mostly documented but it's that mostly part that gets a lot of devs.  Further Windows has a mechanism for allowing multiple versions of the same libraries to be on the same computer, something Unixy systems tend to lack (how many times have decisions had to be made along the lines of, we can't upgrade Mac OS, this version of Creative Cloud won't run on the new system?)  Add to that the fact that there's commercial forks of Wine, one being Proton, Valve Software's fork they started working on because of Microsoft saber-rattling about making S Mode the default Windows mode aka no installing software outside of Microsoft Store.

So for what it is, Wine is amazing.  Sometimes I'm amazed that anything works at all, let alone that I can fire up a bunch of games in Linux Steam and they just work more or less the same as they do in Windows.  Ditto on apps that actually work in Wine.  But it tends to be older software because the undocumented/poorly documented APIs tend to be moving targets.  And of course because Wine doesn't have a mechanism for dealing with multiple versions of DLLs like Windows, you end up with projects like Lutris and Bottles, where they have mechanisms for installing multiple versions of Wine, and installing individual apps in their own directory structures. 

In the end I kind of don't blame Affinity for not porting.  I remember Corel ported Photo-Paint to Linux using Winelib and it turns out a lot of loud Linux users don't tolerate proprietary software, especially software ported by building Linux-native apps with Windows APIs, when they're not games.  It's probably possible for them to create a build, but the ROI isn't there and then they have to deal with Richard Stallman complaining that Affinity Photo isn't released under GPL3.