3 months ago, my pip joint of pinky got dislocated. Reduced movement, normal strength. Anything to get it back to normal? Having ultrasound therapy

Continue with motion. Need to make sure you can fully straighten your pip joint. If this joint is bent and you can't fully straighten then you should see a hand therapist who can start you with splinting. Once you loose the ability to straighten the pip joint may never return. Flexion will come back once the swelling resolves.
Pip dislocation. The stiffness after a dislocation is normal. Continue with a therapy program am it should improve.
Pip joint. Agree this is a common issue typiically 6 - 9months of post injury swelling is common. Stay with therapy especially what you do on your own at home.