Making RA4 prints from color negs is easy. Doing it well is another subject, just like anything else.
Chromes can be done in darkroom via interneg, but that is an advanced skill which even pro labs rarely
did well, simply because they couldn't afford the labor to do it right. But the actual output medium of
scan to laser is essentially the same in terms of paper options, so you can still do it all with an enlarger
and basic darkroom drums or feed processors. And you can get a more seamless result in terms of detail
and tone transitions. This is not the appropriate forum for digital versus optical, but they are parallel
paths to equally high-quality results under ideal circumstances. 6x9 film is particularly challenging because it's small and flimsy, and requires more spotting than sheet film, scratches more easily than
35mm etc. It's easier to retouch via scanning and Photoshop. But where sheet film is involved, I'd far
rather have true optical enlargements, if optimum quality is your concern. I realize there are some supply and service issues in Australia, but you should be able to acquire basic RA4 supplies there.
Portra sheet film can be used for excellent interneg work, though it helps to have color masking skills.