If you are going to go off property not sure Id recommend the Disneyfied Irish Pub at Raglan Rd - not worth the trip IMO.
I'd check yelp for Irish pubs near USO or just stick with Pat O'Brien's.
At both USO and Disney you are going to pay way too much for a drink, the price of a pint is shocking.
Off site will be a better value but its hard to say what the pubs near Universal will be like - may be sketchy IDK.
Also reading reviews for The Paddywagon it looks like they did not even have Irish music on Saint Patrick’s day.
Lucky Leprechaun might be OK, food seems sub par, but they have live music on Saint Patrick’s day.
Guinness is $8 which is about average in the states - Finnigan's in Universal is $12 - so bit of a difference - and Finnigan's closes with the park. Guinness is 10.75 at Pat O'Brien's.
I'm guessing the music will be better off site as well.