Finer Time Increments for "Unavailable" Status

It's very common for us to set our status to Unavailable when going to lunch, or when commuting, or when on an important (but maybe unscheduled) call. However, the time increments we can put in (for "back at") are only in 2-hour increments. It would be very nice to have an "in 30 minutes" and "in 1 hour" option in addition to the other options in the list. Or maybe just a "back by" rather than "until" option?

If I get an important phone call and briefly click "Unavailable" with the intention of clicking it back to "Available" it always says "Until 13:00" or something that is quite often much longer than I plan to be unavailable for.

Instead of "Unavailable until 13:00", having an option to just say "Unavailable. Back by 13:00" or something like that would be less confusing. In other words, make it clear the unavailability is an upper limit rather than when I'm actually planning to return?

I'm not sure which of these solutions is best, but at the moment the Unavailable indication is a bit awkward. Having a better way to communicate that status would be very helpful for remote teams...