The main homepage should stay simple: teancum.me for the person, and subdomains for projects that deserve their own identity.
This keeps the mental model clear:
teancum.meis the personal home and index.teancum.me/projects/mypage-system/is a project write-up.mindmonkey.teancum.mecan become a separate product or experiment.
Why subdomains help
A subdomain can point to a separate GitHub Pages repository. That makes it easier to change a project stack later without disturbing the homepage.
For a small project, that separation is often enough. There is no need for a monorepo, reverse proxy, or shared backend unless the project has outgrown static hosting.