My humanstuck beta troll career headcanons:
Aradia: she is too much of a free spirit to stay in one type of job for long, so I think she would hop from job to job, never staying with one for longer than 3 or so years. I also think she would mostly choose jobs that are outdoors, physical, and/or have long bouts of time off built into them so she can go ghost hunting or backpacking or what have you. Some jobs I think she'd do: school custodian, graveyard maintenance worker, peace corps volunteer, lifeguard, bartender for a cruise line, tour guide, Park ranger, etc.
Tavros: stuck in retail forever, but I don't think he'd be unhappy with it. He could work his way up to manager, and he'd be a bit of a pushover but a good manager overall. Once he finds a place where he feels respected by his coworkers he stays with it forever. Bonus points if the store is a "nerdy" store, like a game stop or a barnes and noble or something. (He'd like their board games)
Sollux: obviously something with software, probably a developer or something. I see sollux as someone who's really only concerned with the pay and not how fun or ethical the job is, so I can see him doing back end development for palantir or black rock or something, or doing generative AI development
Karkat: the only important thing is that he needs to be helping people, and getting paid pennies for it. Being an EMT, CNA, social worker, office worker for a nonprofit, public servant, nurse drowning in student loan debt, WHATEVER it doesn't matter he just needs to be breaking his back for others and broke. Bonus points if he works with cancer patients.
Nepeta: she is a Blue Collar Woman if I've ever seen one, specifically a rural blue collar woman. I could see her as a dairy or beef farmer (but like a worker on a large scale farm, not someone who owns their own farm), car or semi truck mechanic, farm equipment installer, butcher, etc.
Kanaya: I have two options that I like for her: I like making her an arborist, bc it's a very cool career and also incorporates her chainsaw. But I also like thinking of kanaya as a doula or midwife, as a way to draw in her arc and jadeblood duties. Maybe she could be an arborist for 10 or so years after college but becomes a doula after an injury or something.
Terezi: Attorney. Obviously. While I do think she'd be drawn to being a prosecutor like in the comic, I do see a universe where she gets bored with managing plea deals for drug possession cases and goes into tort law instead. Or maybe medmal?
Vriska: office worker; spreadsheet filler. A true menace to all of her coworkers. I'm not dead set on this but I think she might be in HR; I can see her enjoying the power it gives her lol
Equius: mechanical engineer, doing whatever mechanical engineers do. Like sollux, I can see him working for some awful company making bombs or whatever.
Gamzee: he's a difficult one because gamzees behavior and future are so dependent on the au. With his money and personality, though, in general I would say making him chronically unemployed is a safe bet.
Eridan: goes into the navy. Idk how long he stays in it, but it's for a fair bit. After, he might go into conservation, or academia, or be an office worker, or be an unemployed chronically online alt right extremist. Whatever happens next is up to the specific au, but he 100% goes into the navy right after college. (Or even during college).
Feferi: god feferi is a hard one. I tend to think of her as someone who is obsessed with changing the system from the inside, so I can see her taking over a parents company, or going into politics, or becoming a doctor--as long as it's a position of power. The only steadfast headcanon I hold for her is that she stays in sports after finishing school, and does professional sports alongside her day job. Like she could be an Olympic swimming candidate or an NFL cheerleader in addition to whatever her day job is.