Obscure-ish details that I'll clarify:

There are intentional innaccuracies to some of his products. The Danny Phantom origin comic was written by Danny, slightly drunk, while he was on call with the rest of team Phantom. It's art was made by Dani, and it was edited by Lancer!

Lancer also makes novelisations of Phantom's fights with intentional inaccuracies written in. On the cover of his version of Reign Storm, for example, he has the Crown of Rage and the Ring of Flames. They're also palette swapped.

Danny is the Ghost King, but that doesn't pay either. He wears the ring and the crown appears as a tattoo in his human form.

He sells mugs with his logo on them, cheap plushies of himself, regular thermoses that look like his own, Fenton Portal inspired picture frames, Phantom costumes- etc.

Danny is not allowed to sell heavy, offensive weaponry on account of the Incident.

He also sets up little attractions, and holds Amity Park tours in nice weather.

I really like considering what non-Phantom-Planet-compliant Danny's adulthood must look like if he was stuck defending Amity Park from ghosts, and how he'd balance working full time with being a flight-risk. He could never really be a reliable employee, so... Why not own and operate your own business? Who's going to fire you for chronically being late or taking too much unscheduled leave? This AU idea is inspired by those "I survived my trip to NYC" shirts, and Danny's annoyance in Reality Trip when he finds someone selling bootleg comics about him. I figured it'd be pretty funny if he decided to capitalise on his likeness.

And its also inspired by Grunkle Stan from Gravity Falls. Danny fully would lean into the tourist trap vibe in an effort to blend in with his family's shakey reputation. Plus- an obvious con-man couldn't possibly be connected to the good and virtuous Phantom, could he?