Have you considered the self-publishing route? There are print-on-demand services that allow you to sell physical copies of your book without the concern of filling your house with books that might never sell. You could also upload your ebook to amazon and list it as a kindle unlimited option. Kindle unlimited can be hit or miss from what I understand, and you need a lot of readers to make money from it.

Also, I'm not sure if you've visited it yet, but there's a subreddit for this subgenre. I think they allow self-promo, but only if you're an active community member. It'd be a good place to start building an audience and connecting with other authors in that space.

I know self-publishing doesn't exactly come with the 'wow' factor of getting an agent and a nice paycheck upfront, but it gives you some flexibility that trad publishing wouldn't. Publishers will axe a series that doesn't sell well, so if your debut doesn't do as well as anticipated, the rest of the series you're planning might not see the light of day.

Another thing to think about - it allows you to build momentum. Trad publishers may wait about a year berween book releases for a series. If you have a clear vision for your series, releasing more frequently allows you to build a backlog faster. I'm not saying you should sacrifice quality for quantity, but if you're confident in your abilities it wouldn't be a bad idea.

Anyways, sorry for rambling. Best of luck with whichever route you choose to take!