For a thought experiment, why don't we try to identify specific use cases in which it would make sense to have a foreign UnionPay card.

Criteria:
-POS machine that only accepts UnionPay cards
-purchase amount is greater than 1000 (I'm arbitrarily assuming neither ourselves nor venues have patience to do more than 5 Wx/Ap scans)

Scenarios that come to mind:
1. Meal at imperial cuisine type restaurant that doesn't get much private business
-I'm guessing many of us have been to these dinners, though not so often since 2013
-I honestly wouldn't know how to pick up the tab, but surely they have POS machines?

2. KTVs in tier 3 or lower cities
-the problem here is that a solid portion of the huge total outlay probably needs to be settled with cash (or Wx/Ap)

3. Antique furniture
-one of my friends, who works for a shipping company, repatriated before Covid really hit and part of his relocation package was a 40-foot container for him to pack at his own discretion
-he decided to buy a variety of opium beds, tables, chairs, screens, cabinets, etc
-when shopping for that type of stuff, you probably won't get the best deals if you limit yourself to merchants who can accept Visa/MC/Amex

5. Spas/bathhouses
-definitely possible

6. Hotels/serviced apartments
-when Hyatt or Shangri-La options are nonexistent or unsuitable, you could find yourself in a situation where UnionPay is an acceptable form of payment

7. Bespoke clothing
-I mention this because the one of the tailor threads was recently awoken
-most of the merchants I know of have the ability to accept foreign plastic of all types (i.e. there are POS machines they can borrow, when needed)
-but, this might not always be the case if you decide to go really local

That's all I can think of at this juncture (more ideas are welcome, of course), but I think it's a decent enough sampling to evaluate the utility of keeping UnionPay cards in your wallet these days.