In 2015, I was ticketed in AC PY (so no cabin-based lounge access). TG required a physical card, and photocopied it.
However, this was when the BP said "S100K", instead of the current "S100K - AC*G", so hopefully they no longer require that.
I also used the UA lounge, but I don't recall if I had to hand over a physical card. Their system has always been better at pulling your current status out of the network, regardless of whether you have a current card or not.