Wrote a little shell script that calls the native macOS caffeinate binary to prevent macOS from sleeping. Not a ton of functionality, basically:
default, 1 hour
specify # of hours
turn caffeination off
It has notifications and sounds, which you can of course disable in the workflow editor if you like.
Hope you all like it!
Source code and download here:
https://github.com/paulsri/alfred-caffeinate