NUC Hassio image question

I plan to migrate from my Raspberry Pi to an Intel NUC this summer.
Since Home Assistant will be the ONLY app on the NUC, will the NUC Hassio image on the SSD be all I need?

What do I lose without Windows or Docker? (I still haven’t found a comprehensive explanation of what Docker is or why I should want it).

Hassio always uses Docker. In my initial testing with Hassio in a VirtualBox VM I found installing Hassio on (Docker) Linux more stable than the HassOS image.
HassOs kept losing network connection, requiring a reboot.

So, my Hassio on a Raspberry Pi that was installed using the Hassio image from Home Assistant is running Docker?

Yes. The Hassio image is
HassOs hypervisor
docker
Hassio Supervisor container
Home Assistant container.

Hassio addons are all docker containers.