I don’t think multisite is functional for this for a variety of reasons (including small scale of what the subdomain would be fore, interface access, plugins, etc.)

I have a single page that I would like to be accessible at subdomainname.website.com but want it able to be edited by my content users from the normal page interface. Essentially functioning exactly as if it were really just website.com/subdomainname but the url in a user’s window is subdomainname.website.com

I don’t actually know if it’s possible to set this up, but search hasn’t turned up anything for this use case, just points to multisite, which I don’t want to use.