I don't think Jobs could have done much with Sun, or much more with NeXT, which had pretty much run out of road by then.
Sun was professional, Jobs was consumer. Jobs needed to be top dog and in charge of concept, and he couldn't have done that at Sun. He also needed some constraints and consumer focus, which Apple provided.
NeXT was basically a vanity project. It was poorly run from a business POV, but developed some decent tech. The real primary motivation wasn't to make money, it was to keep some attention on Jobs and maintain his profile as an Important Innovative Person.
Sun was engineering-led not image-led and wedded to workstation/server. That market turned out to be a relatively short-lived spasm - a legacy of the mini market pioneered by DEC - in a much longer consumer-oriented tech history.
So there was an impossible tension there.
It might have worked if Apple had remained a completely independent division and Jobs had been given a free hand to run it. But that was never really remotely likely.
It might also have worked if Jobs had any interest in the server/business market. But he really didn't - possibly because it was "boring" and not mass market, which meant less attention and praise for him.