Respectfully, and I do mean that, then Spelljammer will fight one every bit of the way, and I would humbly suggest that those who are seeking that kind of experience would be better off looking at Starfinder or something else. Spelljammer is galleons and crab-ships powered by magic users in space. On a live-action SF scale, it has more in common with Star Wars and Farscape than it does with Star Trek and The Expanse.
Please note that it is not my intention to make a judgement on preference here. I just believe that using Spelljammer to get a more “fantasy races and magic in a sci-fi setting” will cause too much cognitive dissonance, as the central conceits of Spelljammer affect the math, the feel, and the style of games.
It took me a long, long time to grok SJ. I thought that it was stupid for 30 years, since of course planets and other solar bodies don’t work like that, and the writers had to have known as many great discoveries occurred prior to their births. I was limited by my rational understanding, which caused me to despise the setting as stupid and for the ignorant (What? Do I have a problem with being arrogant and have to put forth extra effort to fight it? Noooo, what gave you that idea?). It was only after rediscovering the fiction I loved in my childhood that I began to see the beauty of the setting as it is presented.
Again, I mean no disrespect, and if my advice is no welcome, please feel free to ignore. All of the above is my opinion only, and may be idiosyncratic to me (which happens a lot).