So what’s the magical percentage of market share that gets Adobe to port their proprietary software over to Linux?

Something more than what it currently is.

But as a linux-only user since 2007, it's my opinion that this sort of thing is less and less of a problem for most (note I did not say all) use cases.

There's very few things I have wanted to do with a computer (as a tech enthusiast since the 80s) that isn't doable on Linux. At this point I find most things I personally want to do are easier on Linux.

Gaming is coming along nicely thanks to Proton, which is not as good as native support, but which is still such a turnaround from even 10 years ago that it's pretty amazing.

Non-gaming applications usually (not always) have a Linux equivalent that requires nothing more than decoupling what you need to do from the software you think you need to do it. That's a hard sell if your boss or your teacher tells you all your tasks MUST be done in tool XYZ, but for other things it's not so bad.

99% of what a non-professional thinks they need photoshop for is going to be doable in Krita or Gimp for example. Inkscape and Blender are well regarded for their purposes even outside the Linux community, very few people are really doing something in Word that can't be done in Libre Office Writer, etc...

This isn't intended as a campaign speech for Linux - I've long ago realized that for various reasons it's not a good fit for some folks, or it could be but they aren't interested. That's fine, IMO. However, for the vast majority of what people use a PC for these days, I personally am doubtful that Linux is an obstruction to completing those tasks so much as it might be a paradigm shift for folks to rethink how they intend to complete those tasks.

It's been many years since I've even wanted to run anything from Adobe on Linux. YMMV.

If they support Macs then whatever these things' market share is, I suppose.