There is also the lesser known, but quintessential space game: Space Rangers (GOG). It takes a little figuring out, since it’s a Russian game from 2003 (and a successor of the 1999 game) and they kind of tend to be obtuse like that; but, its genuinely the coolest space sandbox I’ve played. It’s kind of a space Mount and Blade: you can fight aliems, you can trade, you can be a mercenary, or a pirate, and the game accomodates for all of that. At whim, it switches between the core X4-esque gameplay to an RTS, or to a text quest, some of which are basically an entire game of their own. The English translation is a little spotty, but it’s good enough.

Mandalore made a video about it some time ago.

It’s also got a ton of mods! Though not all of them have translations.