Should claifiy my query.
UA BP alone should work for UCs -- no card needed.
A virtual card should work for partner lounge. What lounges are requiring physical UC cards instead? In last year or so, since the rules changed.
As a UA Lifetime *G, I have not been asked for a UC membership card for years (need a membership only for domestic UCs). A BP is sufficient for UCs and use *G for partner lounges.