Subdomains as pages

I have a new project where I’d like a singular WordPress website that serves as the back end for multiple “microsites” on subdomains as well as a “hub” website on the main domain. In other words, I’ll have a custom post type for microsites in the back end and I want to be able to map each custom post to a subdomain.

My original idea was to set up each subdomain as its own Frontity project and link to the same back end, just customize the Frontity settings for each to have the correct subdomain. However, now with the link pre-loading and generally how Frontity can run as an SPA after loading, I would lose all the speed bonuses of Frontity intra-sital navigation.

So can I use subdomains instead of pages in a Vercel-deployed Frontity project? So instead of (like a standard Frontity project would use for a page), can I use for the page? How would one do that?