@springwillow I'm not a doctor, but this is Reddit so I'll share my experience.
PT for a baby usually isn't heavy intervention. The physio we're working with for our daughter has been lovely, and the exercises just feel like extra games for mat time. There's only so hard you could 'train' a 6 month old anyway, so it's all pretty low impact. For mine it's good to jump on a low impact therapy early.
Maybe it'll help, maybe the problem would have corrected itself anyway, I don't see much harm in giving it a go anyway.
We did have our daughter in a Pavlik harness for a few months, and as we were a borderline hip dysplasia case I question whether putting her through that was worthwhile. I don't question the PT though, since there's really no downside to it.