I am developing my own application on Next.js, similar to Notion, where it is possible to publish your notes as a site. Right now these sites are available as just pages on my main site, but I want users to be able to connect their domains to these pages

Example:
The user has a note site in my application accessible by domain mysite.com/note/[pageId]
But I want him to be able to connect his domain and for this note to be available on this domain. How to implement this?