Currently it is possible to change start and end time of work units using two input styles:
I would suggest adding a third input style that could perhaps best be described as "wheels" or "spinner".
I think iOS uses this UI pattern a lot and even though I use Android I must admit that it works really well.
In the app "Baby Daybook" they have really nailed down frictionless updating of entries for what happens to your baby, including changing time of events. It is quite often that you start a timer and think "oh, I started this a few minutes late. Let me wind it a few minutes back". Using the wheels allows you to directly drag the minutes a few ticks and save it again.

See screenshot. Similar to Working Hours, in the bottom left of the modal, clicking the icon lets you cycle through all three types of inputs. But I only ever use the wheels and I would really like to see this added to Working Hours since it is one of my only pain points left.
WorkingHours version: 2.12.3
Operating system: Android 12
Device model: OnePlus Nord