I have 3 of these at the moment. 2 regular and 1 Pro.
There is no PoE in any of them as they are more so catered to Home Use.
UBNT offers wall plug in access points like this for home to extend coverage
802.11ac Wave 2 access point that plugs into an AC wall outlet to quickly extend wireless coverage and improve throughput. The Access Point BeaconHD (UAP BeaconHD) is a 802.11ac WiFi access point that utilizes Wave 2 technology and bidirectional uplink design to connect with and relay the...
store.ui.com
You can add PoE switches as well for a more robust network and this works just fine.
The ONLY thing so far for me that does not work like the USG is "automatic vpn setup" or the ability to control the Dream Machine from another controller.
You can do site to site VPN but they are manual setup "for now" but appears an update is coming to include automatic.
The controller software is built-in and it can control other UniFi devices, it just can not control another Dream Machine.
You can have multiple Dream Machines on your ubnt account and can easily switch between them but they can't control each other with the latest software as of today.
If anyone wants further info I would be happy to share.