Sequels are a tricky beast...
Upfront, I want to say, if you're making a sequel because you're enjoying yourself and it's just fun to explore your characters, then that's totally okay and you should just do it (personally I do write sequel and spinoff scenes with my characters, I just keep them all private as a fun way to explore and indulge in stuff that's too rambly and fluffy for the comic).
But... you did ask "What would be the prospects?" so I think it makes sense to discuss how well sequels, prequels and spinoffs can perform. With the disclaimer that performance doesn't have to be important to everyone. Just to explore it though...
The easiest way to make a sequel or spinoff comic and still retain readers while attracting new ones, is to make it so you don't need to have read the original. So don't stick a "2" on the end, don't be reliant on continuity to understand and plot and have characters, or at least boxed text reintroduce concepts and people if continuity is needed. Otherwise, keep the characters largely recognisable, so readers who liked the original might try the sequel, or new readers can read the sequel and then go back and read the older story.
If it's a sequel or spin-off that requires the readers to have read all of the first one, things are a lot harder, because there's likely to be at least some drop-off in readership, and there's a lot of content to consume as a baseline before they can get into the new thing, so picking up new readers is harder. They don't generally perform so well. They can still do well if the original had a really big following, by renewing the interest of existing fans and building buzz around the series online...but the numbers do have to be pretty big for it to be viable in terms of readership and money. (disclaimer once again, I'm purely talking about the numerical business side of things and am not intending to put down anyone who makes a sequel for personal fulfilment, happiness or a sense of community, because for some people, those are more important, and that's fine!).
Switching between comics and novels, while definitely good for just getting the content done, is usually bad for retaining readership. Comic readers and novel readers are often looking for a really different experience, because comics have pacing more like a movie or show, and what works well in comics and novels can be pretty different. It might be best to assume the readers of a novel spinoff will largely be different from the original comic.
So on a purely numbers-focused level, the best approach is to have the spinoff or sequel be one of two things:
It's made in response to a large and hungry audience of existing fans who want more content! It should be largely in the same sort of genre or tone, style and format and can contain as much continuity and references back to the original as you like. There may be an initial drop-off, but if the fandom is big enough and it's a good story, the buzz around the series will bring in new people.
It's a side thing intended to catch the interest of new people who maybe don't read the original (or have never come across it) because it's not in their preferred genre, style or format. It doesn't rely on a lot of (or maybe any) story continuity, but has enough stuff with great shared characters and setting detail that if the story is great and that setting and characters seem intriguing, there might be crossover between the two works. Mostly though, it's its own thing with a different audience (which can be a solid tactic, honestly, multiple income streams and showing flexibility isn't bad).
