Projects as Gitlab page subpaths

Hi! First post. One of the nice things about GitHub pages was that subprojects automatically mapped to subpaths on the custom domain I had set up.

Is there a way to host projects on subpaths if the custom domain is setup on the root? I have pointing at

But other project pages like aren’t routing properly (e.g. 404s). Has anyone done this before, is it possible?

Edit: looks like it’s being worked on here for subgroups, but that doesn’t apply to me (an individual user).