I understand that this request is a long shot because it probably won't directly benefit to Pi-hole itself however I'm working on a personal project that requires an adblocking list exactly like gravity produces. I looked at the amount of work that has gone into reliably fetching, parsing and processing adblocking lists and it's a lot more complicated than I initially expected.
Have the maintainers considered decoupling the logic regarding fetching/processing adblocking lists from the logic of interfacing/restarting Pi-hole? I.e. moving the Pi-hole specific stuff to a wrapper function so the core logic can exist independently. This way, in the spirit of open-source, the work put into this can be used in other projects/places where people need to process host/domain lists.