PushLive should with both subdomain and subdirectory WordPress setup.
Though if your main site is https://example.com you will still need to create a subdomain like https://stage.example.com or https://dev.example.com for your staging/development site.
in the case of setting up WordPress to use subdomains instead of subdirectories, I think you’re going to get multi-level subdomains (i.e. https://something.stage.example.com) – so this all depends on whether your server allows it and if you have the ability to set it up. Here’s something I found that might shed light on the subject https://serverfault.com/questions/278295/subdomain-of-a-subdomain
As always, perhaps there’s something we missed in this process as we always work with WordPress subdirectory setup for our sites or maybe I got your question completely wrong. If you have any issues, please let us know so we can resolve them.