More datapoints for US merchants that I tested with the US-issued ICBC UnionPay card:

Trader Joe's - UnionPay Chip supported natively like other chip cards (receipt says ICBC PBOCCARD); will test contactless there in future

Safeway (grocery store) - Still swipe-only UnionPay in PIN debit mode as tested & reported before, but wanted to add datapoint of $200 cashback at the self-checkout working recently, as I wasn't sure if others had mentioned trying with a high cashback amount on this card; Until Safeway supports UnionPay chip cards, this is a great ATM alternative

Smart & Final (grocery store) - Swipe-only UnionPay but works in PIN debit mode, so up to $50 cashback ($100 and $200 requests failed)

O'Reilly's Auto Parts - Swipe-only UnionPay as a credit card; has UnionPay sticker on terminal, but no chip support