Are these steps possible:

1. Create an image of the currently running 16.04 Host install. (Save a backup.)
2. Install KVM on the current DevNet.
3. Launch a copy of the 16.04 install in KVM as a Guest.
4. Reroute traffic to the 16.04 Guest.
5. Uninstall 16.04 Host. Leave 16.04 Guest running and accessible.
6. Install 20.04 Host for managing KVM.
7. Install 20.04 Guest on KVM. Set it up. 16.04 Guest is still running and accessible.
8. Reroute traffic to the 20.04 Guest.
9. Shut down 16.04 Guest. (Save snapshot.)

Alternative Plan:

1. Create an image of the currently running 16.04 Host install. (Save a backup.)
2. Install 20.04 Host for managing KVM.
3. Install KVM.
4. Load 16.04 image as Guest on KVM. Reroute traffic into it.
5. Install 20.04 Guest on KVM. Set it up. 16.04 Guest is still running and accessible.
6. Reroute traffic to the 20.04 Guest.
7. Shut down 16.04 Guest. (Save snapshot.)