Accountant position in VC firm and hope to transition to associate down the road

It's possible, but might be tough. Depending on the size and team structure of this firm, one approach would be to express interest in learning more about that side of the business once you've proven yourself there. If they are open to it, you might be able to gradually assume some responsibilities/projects that are more on the investing team side of things.

Assuming you want the staff accountant job though, I wouldn't bring up the possibility of transitioning during the interview, and I wouldn't accept an offer assuming that this was a likely possibility. Relatedly, you may run into internal politics issues depending on the personalities you're working with. It's a tricky approach that you should be careful about navigating. You obviously don't want to make the operations team look bad or give the impression that you're not committed to doing the job you were hired for.

Whether this works or not is pretty firm depending. I think you'd have better luck with a firm that has a small junior investing team since the team is more likely to be capacity constrained than if you were to go to a place with a large number of Analysts/Associates.

It's also more likely to work for VC than PE.

Good luck on the interview!