WTH Why can't I easily offset an input_datetime based automation


I want to create a morning and evening routine using an automation.
I use an input_time to trigger the morning routine (this works fine)
However, I would like to use an input_number to specify the number of hours I would like to sleep.
Another automation would then use the same input_time and offset it by -input_number hours
This is really hard to do.
Why can’t we offset a time trigger by a value?
Why can’t we use an input_number as input of a time offset?

Kind regards,

There is already a WTH for this. Please vote here: