So I gave this a shot, but got some strange results
alg.subprocess.start(["substance painter.exe", "--mesh", meshPath, painterPath])
What this ends up doing for me is opening a new instance of Substance Painter (with the updated mesh) that is somehow tied to the instance that spawned it. I guess through subprocess. If I reload the plugin in the first window, the second window disappears.
Not sure if what I'm doing wrong here... any ideas?