Modbus device_class duration - how to format display value?

In my modbus yaml I am using “device_class” in order to get the appropriate icon (definition of icon is not allowed in modbus or I am not aware how to do).

For unit_of_measurement: ‘h’ I now get the icon as expected. However value is shown like 2454:00:00 instead of 2454.
mpdbus hours format
Since I could not find how to restrict value to hours only I am asking for help how to define the modbus entity in question.
Thanks for any help/suggestions

Remove the device class and add the icon in the frontend by editing the entities card.

Thanks, I was aware of this possibility, but I am seeking for a solution to do it just once and not with every occurance of the entities in every card. Similar to precision for numbers

Any method to accomphlish this ?