There are absolutely no rules saying you can't do both
My main series that I've been working on for the past 10+ years has been novelized since the start and then got a comic version in 2014 that's still running. I update the comic when I can and basically upload the entirety of the books as soon as they're available (ex. I just uploaded the novel version of Reaper, which is complete, but the comic is only about halfway through; I'm hoping to have the second book, The Child Chapters, ready for the summer). You don't have to read both, but reading both will get you the full narrative AND visual experience (as the comic version as a lot more visual stuff that can only be portrayed so much in novel form; and the novel version has the advantage of being able to delve further into the characters' inner monologues, and have extended footnotes without it having to be drawn).
You just have to ask yourself how much work you're willing to do and whether or not it's feasible to do. But you're not obligated to do it one specific way, you absolutely can do both (or one of the two if you decide one way would work better; I can vouch for the fact that DRAWING a series is a MUCH bigger commitment than writing it, especially if it's as long as the one I'm currently working on. Like the novel version is like, 300+ thousand words lmaoo there's a reason the comic version is barely even halfway through after almost 6 years; meanwhile I blasted through the first manuscript of Reaper in 2 months and we're currently halfway through writing the first draft of The Child Chapters).
If you're nervous about the commitment, that's 100% okay. You can always release a few chapters of the novel version of your story first and then decide from there if you want to offer it as a comic as well
(i say that because it's obv gonna be way easier on you to do novel version first and then comic versus the other way around, I can safely say from experience that the novel will be easier to finish than the comic lol)