Input_datetime with has_date: false not convert as_timestamp

Configuration
1

Hello.
I am trying to convert data from input_datetime entity to timestamp format:

{{ as_timestamp(states(‘input_datetime.both_date_and_time’))}}

But for some reason this is only possible if the input_datetime entity has both a date and a time

When has_date: false, this causes an error.

Maybe this conversion can be implemented in some other way?

2

All input_datetimes have a timestamp attribute, so:

{{ state_attr('input_datetime.time_only', 'timestamp') }}
4

Is there a way to convert just a time into the next timestamp that time will occur? I am making a coffee timer and want to set it to go off at 6:00am. I want to make a card that will display that the coffee will be made at (If the current day is Sunday) Monday at 6:00am

Essentially I want to add the date to a time that will display the next occurrence of that time.What will the full timestamp/date be the next time it’s 6:00am.

If I try to do a conversion on the above, it sets the date to 1/1/1970 at 1am

Thanks in advance!