Timed delay scheduler

[nvllz]

Is your feature request related to a problem? Please describe.
Say I want to set a reminder in 148 minutes. Now I have to calculate the desired execution time myself, which can be problematic in some cases.

Describe the solution you'd like
I'd like an option to choose between exact time and time delay so I can select the latter and easily set a reminder in 20 minutes or even 3 hours and 30 minutes without having to calculate the time of the expected reminder.

Describe alternatives you've considered
The only alternative is to use the built-in Timer app, or quickly calculate the desired reminder time by oneself, but it's not an solution.

Additional context
I see it as an additional button under the "Select time" label which, when tapped, displays a handy dialog with a text box for digits and a list box for min/hr selection.

Something like this one: