You said Islam believes in Sola Scriptura. I pointed out non-Koranic authorities within Islam. (Of course, the actual doctrine of Sola Scriptura means the Bible by "Scriptura", so if the Muslims ever started believing in it, they'd be Christians).
Then you start talking about the priesthood of the believer. That's a different subject.
There is no priesthood in Islam - only religious scholars and prayer leaders
Yes. That's why they have no priesthood of the believer. You have to have some concept of what a priest is before you can say that every believer is one.
- sort of like in Judaism.
I wonder if you ever read those books of the Bible near the beginning. I'm thinking especially of the third and fifth. You know, the stuff that wasn't written in Greek (don't worry, they translated it a long time ago), with all the rules about sacrifices and leprosy and suchlike. Lots of references to priests. That was a hereditary priesthood. They're still around. Lots of them have the surname Cohen. There's not much for them to do these days but they do exist and IIRC have a few ceremonial functions in synagogues.
Sola Scriptura just means you follow the written word of teh Bible as your only authority. No holy men or priests or even saints. Sounds a lot like Islam's basics.