I've just launched Notionlayer.
I needed custom domains to deploy some Notion pages such as documentation, news, blog posts, job postings, reports, etc. Basically, I had many small pages and needed lots of custom domains. Many alternatives cost ~10USD per month per site, in my case that didn't make sense to pay for 1-page long documentation.
I was unable to find a cheap tool that enabled me to publish multiple pages to multiple domains, without any branding. I decided to do it to scratch my own itch, and I took the extra step of making it into a product.
The product is focused on making internal pages or secondary pages rather than landing pages.
It's very easy and cheap to get started. You can check it out here.