The HAOS can “see” the integrated Bluetooth, but it is not able to function properly.
I have three USB dongles: BT, WiFi, and Sonoff Zigbee
Similar for WiFi, internal is not available or supported by HAOS (doesn’t even “see” the integrated WiFi).
Yes, I use the wired LAN port for my main network access. The WiFi dongle is to provide a same-subnet point for Alexa devices to communicate with Home Assistant.
Explained: my Alexa subnet is only able to access other Alexas, the HA Server, and the internet. I don’t want Alexa to be sniffing around on what else goes on!
Now, it is possible to temporarily join one Alexa Echo device to my main network for Discovery, and everything still works when isolating Alexa back to the restricted subnet. However, if / when I make any changes in HA and want to update Alexa, I must first put one back in my main network, do the discovery, etc. and move her back to the isolated network.
That’s why I use a WiFi dongle on my Mac Mini.