Yes indeed. I could not remember doing this when I installed OMV2 back in the days.
You can create the USB-stick on any computer and just plug it into your server. make sure it boots from USB.
I created the USB stick with OMV6 on my laptop (I created the final install, I don't mean the installer!).
It was working fine, I added the omv-extra plugin and some more plugins and changed the password of the web GUI.
All of this while the USB was plugged into my laptop.
I then moved this stick to my server, booted the server up with changes in the BIOS where the stick was shown so that it is first to boot. However, this did not work. I have two entries for the stick: USB and UEFI and I setup both beeing before the SSD with the old OMV4.
However, it is not booting from the stick.
Is there a dependency on the hardware? Can I not move the final installation around to another system?