Do Not Sleep custom timings

I use my MacBook as a 3rd screen during my remote workday and use Do Not Sleep to keep it awake.
However, the default time out options are not fine-grained enough.
It jumps from 6 hours to End of Day, which means I usually have to set it twice during my ~8.5-hour workday and then cancel it at the end.
It would be great to be able to enter either a custom "how long", or perhaps a "do not sleep until" to specify an exact time, or both!