Am I biting off more than I should?

I'm a lifelong hobby programmer but new to Indie Hacking / Bootstrapping and I'm wanting to build a software product that would serve businesses similar to my existing small brick-and-mortar business which does apparel decoration, signage, printing, and vehicle wraps.

There are plenty of products that do just one portion or the other (apps for just apparel decorators and apps for just sign makers for example) and fewer that claim to server multi-decorators though most are lacking in one way or the other. I've tried dozens of the existing solutions out for my business and not been happy with anything so far other than using Trello+QBO to manage my shop. I realize this will not scale well if I want to build my business and will be cumbersome especially if I want to put others in various roles.

The app I have in my head would be a SaaS product that would be like a "Business Operating System" (BOS) that would basically be the portal for running a business like mine, only minus the design software (adobe creative suite).

Here are my problems:

1. Self doubt:
   I know other similar businesses use various existing solutions to run their businesses successfully - so why would they bother using mine? Maybe I'm trying to do too much, even if it's what I'd want for my business, am I a-typical?

2. Scope:
   This would be my first such project and I'd really like to do it, but I'm having a hard time boiling it down into smaller chunks that would be useful. The MVP for my idea is not particularly small (it's like a CRM+CPQ at minimum). I can break it down into a roadmap, and I have but I don't think it would be marketable until a majority of the entire product is completed. I suppose I could break out just the CPQ aspect of it.

3. Focus:
   I've been in my industry a while, and I'd kind of like to work on something outside of it, but it is what I know. I have a couple of other ideas to work on but they are in areas I know much less about and seem equally overwhelming for that reason even though the technology side would be simpler. I'm thinking of starting one or two much smaller scoped side projects to switch to when I'm lacking motivation to work on this main one (one's in STEM education, the other in crypto trading - both areas that are new to me).

4. Market:
   Again, I am in this space already, so I have some peers. But it also occurs to me that since my current business serves other small business (we're 90+% B2B) that I actually personally know a lot of business owners in other fields as well, even more than I know my small handful of colleagues. I feel like if I could identify a need within a niche of the business owners that I already serve I could make early sales easier and have potentially a large initial market just by the number of business owners I know. My existing business really hasn't been niched down beyond small/medium businesses in general so I serve a rather broad sampling of business owners. That said, I'm in a smaller suburban market. The only problem I see with this is that I don't know my client's businesses as well as I know my own, but maybe I am overly concerned with this.

I'm currently taking a SaaS course to brush up on the technology side (I haven't had much time to keep up on the hobby stuff due to kids and business taking all of my time for a while).

I'm considering trying the "building in public" thing for this project, as intimidating as that may be to an introvert like myself. It's a concept I was unaware of until I joined IH recently.

Thanks for listening. Any thoughts or advice is appreciated.