Instrument Proficiency trait
Pick the lute in Druids grove to help her, succeed in two charisma rolls and your character gains the trait that allows to use musical instruments. https://bg3.wiki/wiki/Proficiency#Instrument_Proficiency, https://bg3.wiki/wiki/Permanent_Bonuses
And you get unique Lute.
Extra Superior Bardic Inspiration
I haven’t heard this talked about anywhere, but Alfira can give you Bardic Inspiration as a Class Action, using a d12. It doesn’t require a Bardic Inspiration charge, it’s just on a Long Rest cooldown.
I’m not 100% sure of the unlock requirements, but here’s what I did to get it: my main character was a Bard, and I had another squad member play with her in the Emerald Grove to unlock the instrument proficiency. Then, after killing Ketheric in Act 2, I spoke to her in Moonrise Towers and she asked to play with me again. I said yes and we Performed together, and afterwards I saw that I had a second Bardic Inspiration action in the tray. Hopefully others can do more testing if this is something new.