Since the current season of the gnostic hymn is about to end the battle pass is probably not worth it.
You have two options, spend 5 dollars for the welkin moon which gives you 90 primos everyday for 31 days plus 300 genesis crystals. Or, wait until after this seasons battle pass to buy the next gnostic hymn pass and farm the daily quests to get primos and a weapon (among other things).
Personally I’d get the battle pass but that’s just me. if you don’t see yourself playing Genshin every day dedicatedly then the welkin moon is pretty good. Just login, get your daily primos and logout.