Another aspect that is important to a lot of people. Especially close quarters combat, because that's where the thrill is. The above ship system granularity is a huge part of this, especially the hardpoints. Right now about every ship can have one front and one rear cannon and a given amount of missiles, which isn't good for ship differentiation either. Would need proper design, and will be a huge multi-faceted project.
It is a good opportunity do lean into the fact that there is no FTL communication in the universe apart from Courier ships and drones, which effectively makes all systems quite isolated from each other in a city-state manner. So there's no Galactic Police, and even neighboring systems can have very distinct security levels,
Multiple hardpoints per ship, with size and power and other limits to differentiate ships more Weapons hardpoint design outline by sturnclaw
Sensors and detection
Shields could work in a more unique manner, instead of just being a regenerating second health bar
Maneuvering should be more important in combat. Figuring out a way to eliminate jousting as much as possible would be quite important important in my opinion.
The above mentioned semi-turn based approach to intercepts could be interesting I think. Like if one wants to pirate, they'd pick a target, plan an intercept, and change that flight plan based on the reaction of the target. And manually finish the last leg of the intercept.
Ship health would benefit from some thought also. The ability to mission-kill a ship by disabling engines for example would be nice. Or disarming them, or destroying a certain equipment of theirs that would keep them from fulfiling their task. Which could also happen to the player.
Ability to put out distress calls (and to react to them either beningly or maliciously)
There are UI-UX considerations for combat as well, both regarding information provided, and aids for the actual combat, like lead indicators, motion trails and such.