Serious Eats used a dry fried minced mushrooms to substitute for, in that case, beef in a dish. I don't know if it will substitute for pork mince in the same way, having no firsthand experience, but it may be worth trying. The results are, reportedly, rich and savory and deeply flavored, lots of umami - which sounds like it would do a similar job of adding depth and flavor to your stir fry, even if the specific flavor added is different.
To make the mushroom mince, they used button mushrooms, well minced and fried until the water had mostly evaporated out and they were deeply browned, and added them to the minced mushrooms they had on hand from the broth in that recipe. With a bonus of very mushroom-flavored oil, to fry in. That's a nice addition, adding flavor and, also, fat (since meats usually add both).
For your stir fry, it seems like a similar substitution might work - start with a few minced mushrooms, making sure they get quite dry and brown by the time you're done. They should give the flavor some of that extra depth and savoriness, just as a meat mince would do. You might want soy sauce or liquid aminos or even something like kombu to touch up the umami flavor a bit more - your stir fry might need a little more since that recipe had other flavors to rely on.