Airbus LOC/VNAV normally flown with LOC providing the lateral course guidance.
Could be flown in NAV, but that's not how I was trained, just as in theory, an ILS approach could be flown as a VNAV approach with NAV lateral guidance.

In this situation, what I have done in the past is flown the RV in Heading/Select, LOC armed to capture the final course, and the FMS cleaned up to the waypoint in front of my airplane. Once LOC captures and I'm on course, I'd arm Profile and wait for the system to capture the VNAV path.

FMS will show my vertical track error and I can watch it count down to the intercept. If I'm above the path, I have to intervene in some way to make it happen. My technique was to use V/S so I could control the descent rate for minor vertical errors. Slam dunk I'd go for the idle descent & boards or make ATC give me a better vector versus accepting a poor setup