> accessible enough for non-programmers and advanced users

I mean unless you also discredit Windows and MacOS as being accessible because there exist pro applications that aren't present on those platforms, Im not sure what your point is.

Gimp, Inkscape, Krita, etc...

They have a SaaS offering, wouldn't it work from a linux box ?

I've tried the online versions, and they're not even close to being a replacement for the proper desktop applications.