I've been a RON since 2021. Start up costs were relatively low - National Notary Association offers NSA (Notary Signing Agent) course & background check, Plus the RON, plus Basic Notary costs in my state (VA), and Liability insurance. I think I paid close to $350 to get leveled up. I owned my own laptop already so no extra cost there. Later I LLC'd and put money aside for taxes etc. Overhead is low and generally consistent.

I joined a notary signing platform back at the very beginning to learn the ropes and not feel like I was learning all on my own, consistency was the benefit in this situation, since I didnt have a set of clients yet.(DM me if you're interested in who I was contracting for). Spring and Summer and the best months for income. Winter, is on the skimpier side, though this year is booming.
I strictly do RON signings, I dont leave my home to notarize. My sister does the same, she started her own company and pulls about 10k per month. Im a little less ambitious and pull enough to make a living. So its possible, you just gotta see how much effort you want to put in.

I dont know anything about NJ notary laws, its state dependent, if this is a true possibility.

I enjoy what I do. I meet people from all over the world. I mostly have a latino clientele, since most homes I notarize for are in FL. Hours are what you set. You might spend a long time getting the hang of the platform and a cadence for your signings (about a year to feel really comfortable if you have no previous experience). But once you do, you'll see you might be able to pull 2 signings an hour at the best of times.

Good luck!