Can you not have the domain redirect to the page? It's not as pretty but it would still be an easy first step.

In any case, thank you so much for this. I have my portfolio hosted on the old Medium publications, back when they allowed for custom domains: https://charliegedeon.com

I just saw the beta of the new publications coming out and it's just not going to work for me anymomre. I was really dreading what I would have to move to but this is actually a perfect middle ground!