Pretty much universally, native speakers say the individual letters U-P-S, rather than trying to say the initials as a single word, so it's rarely an issue. I've heard it being called 'ups' (pronounced "uh'ps"), but the speaker promptly disappeared amidst a cloud of embarrassment... -_-
Because the word 'up' is spoken with the broader (not sure of the linguistic term, but it's distinct from the narrow 'oo' from 'oops') 'uh' sound, the connection you intimate isn't really drawn among native English speakers...
I say this as an RP person, so there may be regional accents that may do otherwise.