Found a campaign you'll want to play!
Cataclysm, released looooong ago in 2022, is a very fun little post-FS2 campaign with a unique premise compared to all the "Sol gate and/or Shivans and/or rebels again" campaigns! It's a demo, so it doesn't conclude its story, but what's there is very good

Honorable mentions so far, dunno if you'll want to slot them in somewhere:
Alcibiades' Gamble is a demo for a cancelled project

, and plays like the beginning of a campaign - somewhat slow-paced, simple missions with not a lot going on mechanically (you shoot down LOTS of fighters lol). FREDding and moment-to-moment writing are pretty sound, though the campaign didn't quite manage to sell the feeling of tension/unease it was going for (it's set in the very early days of the NTF when no one knew who to trust). Kewl music.
The Apocalypse: Vega is an odd campaign marred by spelling/grammar errors, strange presentation (no loadouts/debriefings, and some subtitle text seemingly in place of them), a premise that stretches disbelief (LOTS of Shivans spilled over into Vega from Capella during FS2, apparently), and frustrating loadouts (A Herc with default weapons, including Prom Rs

I get that they're launching everything they have, but
at least give me Akhetons if you want me to disable a Lilith's beam!). Despite all this, the first few missions I played were fun!