I did the laundry list of things and hunted down “Neptune” as part of “season 1 of Shadow Tide” and don’t think any special loot dropped off him.
The Pentagon and DARPA missions are about the only ones that will be sort of a pain in the butt solo.
I wonder how much mileage they can get out of running and re-running the same content over and over. It’s annoying how every GAAS wants it to be the only game you play and angles for the FOMO with time-limited events and things.