I never understood why you did not have a fully populated UNA demo site like you did with Dolphin; both admin (studio) and front end, with set logins (no registration needed) that reset every 30 minutes. We could see and test all power apps on the UNA demo site. You do have some site that requires one to join but no demo site like with Dolphin. The Dolphin demo site was very useful; especially being able to log into the admin to check settings.
No particular reason other than lack of time and resources to set it up. Also, a lot of great UNA sites are heavily reconfigured, so an out-of-the-box demo wouldn't do it justice. Early next year I'm hoping to set up a couple of pre-configured solutions, just as we planned before and allow them to be cloned. We are building infrastructure to orchestrate this.