Fingering is not a risk for any STI or HIV.
When you say "an extended period of time" - what does that mean? A minute? 5 minutes? 10?
Penetration that lasts less than a minute can, in theory, transmit STIs and HIV, but isn't likely to.
Flipping the condom around after putting it on wrong is more of a concern for pregnancy - in theory - than STIs or HIV.
I'm a little concerned that he's on PrEP. That would indicate he has high risk behaviors. Did you ask him why he's on that?
Also, saying he's "clean" - which is a stigmatized word and implies that people with STIs are dirty - means nothing if he hasn't tested to know he's actually infection free. Being on PrEP is good, and means he might be tested regularly, but again, we don't know that.
I'd guess that your chances are low, but I don't know for sure.