I’m a big fan of The Expanse, so let me see what we can find!
All of these are on the Sci-Fi Player unless otherwise specified.
Abandoned Space Station is good for any run-down or abandoned space installation or ship, complete with garbled transmissions. Just turn off the “alien movement” elements (unless, of course, your players end up tangling with the alien molecule mutated creatures!).
Engine Room is a little more Star Trek-y than The Expanse, but it has a lot of good noises that work for working computers, engines, power plants, and then them exploding and melting down too.
Nuclear Submarine has a lot of good mechanical sounds for machinery and hull stress.
The Modern Weapons soundset (actually in Fantasy Player) has all those good shotguns, pistols, etc.
So does Starfinder Handheld Weapons, along with others like shock, sonic, etc, which could be higher-tech weapons or stunning shots.
Starship Weapons has a variety of shipboard weapons, including some missiles that fit The Expanse universe.
If your characters end up dealing with the alien tech (wormhole space), Time Tunnel is a good one for that.
A lot of the Cyberpunk sets (Abandoned Facility, Night Market, AgriFarm, Club Flux, Tech Workshop, Hot Zone, etc) could be very useful for different districts or areas around the Outer planets and Belt.
Frozen Moon has a couple of useful elements, “space suit breath” and “space suit panic”, along with a low oxygen alarm one-shot - very important!
The Sci-Fi player has a couple of universal one-shots for airlock doors (which also work for station doors).
Absalom Station has a lot of good sounds for station life in various areas, both public and mechanical.
Spacedock has a lot of good repair sounds, welding and power tools and whatnot.
Nebula has some good moods of “meteor shower” and “debris field” for getting your ship or station thrashed!
I couldn’t find a sound for mag boots, other than usual steps on a hard floor, and that’s not quite the same.
I hope that helps, and let me know if you need anything else!