I have a Lovelace card on which I display the uptime, firmware versions and other information of my routers and switches. Recently, there is a sensor to query the uptime of the FRITZ!Box, but I cannot find a way to determine the FRITZ!OS version. However, on the device overview page of the AVM FRITZ!Box Tools integration, the version is displayed so that it can apparently be queried.
I would be very pleased to have a sensor or an attribute with the FRITZ!OS version.
This is what my Lovelace card looks like so far: