Sometimes the idea of something is more rewarding than the grind of making that thing work.
Once upon a time I worked for and with an organization that encouraged small business start ups like sole proprietor or very small size. Many people have been in your shoes and not known how to transition from employee to self employed.
The longer you can stay full time where you are the better. There are check lists of foundational tasks for new businesses to get you started. Things like business licenses, business checking account, book keeping/accounting, and getting the basics of tax law figured out. Often folks know how to build things, but the accounting/tax thing is the hardest to figure out. Every state used to have a federally funded small business development center offering free or low $$ training and advice for guys in your boat - these are typically associated with a university in your state. Hopefully federal budget cuts didn’t axe them.
You know how to build things, so there’s no reason why it can’t be set up and operated as a business now, even if you aren’t anywhere close to being profitable. We taught guys to make their side hustle legit so as it grew they already had the business and tax side figured out.
Not to be Debby Downer, but nobody wants to loan you a large chunk of money to jump in with both feet, rent a big space, buy a bunch of Juki machines and have you’re very own giant bubble wrap roll in a dedicated shipping area. You’re going to have to self fund the basics of getting started, and hustle to get sales so keep those commission checks rolling where you’re at. Once you have a functional business and significant orders, then you become more eligible for small business loans and whatnot.
Opportunities exist in niche hunting/shooting, but high end diaper bags will have 1000x the potential customers, so sometimes where a business starts isn’t where it ends up to be profitable.
The downside to a sewing business is every dude with a design and stay at home wife, her girl friend, a cousin, and uncle Jimmy who enjoy sewing in their spare time are your competition.
You’re in a better place than many to get the business started and fine tune your designs and patterns (your cool new design is only as repeatable as your patterns). Good design ideas are harder to come up with than someone who can run an industrial sewing machine, so you have that going for you.
I’m super behind the idea of what you’re thinking about - setting up even a legit micro business will teach you a lot, and that’s 100% applicable to other business ideas you might not have even thought of yet.
Googled “Washington state small business development center” and this was the first link: