I gave it a try (virt-manager 3.2.0-3, spice-client-gtk 0.39-1, these are normal Debian 11 packages). When creating a new VM, it was difficult to comprehend how to attach a debian install .iso as a Virtual CD drive.
I found a tutorial here, which solved it:
PS: when the tutorial urged me to start manually editing /etc/network/interfaces, that’s where I quit following the tutorial. I noticed that a new network interface “virbr0” does get created earlier on. I cleverly used that interface name, when setting up bridged networking for my VM. An average user would certainly have a hard time knowing to find that “virbr0” interface and specifying it for the network interface (of type “Bridged”).
Definitely not very user-friendly, but I got by.
Thanks for the tips. I guess for free software, you get what you get. 