Niche site vs. main site content

I have a main site that's more of a blog than a super-focused niche site. I sell live events, my own products, and occasionally other people's products. The site has decent domain trust and all of the other metrics. I can usually rank in the top two or three spots for a new article if it's not super-competitive.

I'd like to start using my brand to branch out into niche sites that can do deep-dives into content I scratch the surface on with my blog. And I have one lucrative niche in particular to start with (I already get a lot of traffic for this niche on my main site).

My question is this: that niche has a lot of specific content I can cover. I'm creating that content now, but not sure where to put it...

1. On a special niche domain I own

Pros:
- Separate the content to super-focus on the niche
- Make it more sales focused and use a single CTA to get them to buy a high ticket item
- A colleague/competitor of mine ranks #1 with a relatively thin site

Cons:
- I can link to the niche domain from my main domain, but it still wouldn't have the ranking power of my main site

Or...
2. Make the articles Pages under the appropriate niche sub-category on my main site

Pros:
- Much easier to rank
- Enhances my main brand as a source of evergreen information on the topic, rather than just blog posts

Cons:
- Distracting CTAs; I sell a newsletter that discusses the topic and having more than one offer on the site might confuse people or delay purchases
- My main site is more informational than e-commerce, and people may delay making a decision because it "feels" like a library, not a store

Any recommendations?