[sunshinesnacks]

Grid following inverters can do something similar, although their response time is usually limited to the grid operator's automatic generation control (AGC) communication cycle, which is typically on the order of 4 to 6 seconds. And this requires plant controllers, and markets/contracts, to be setup for it.

See https://www.nrel.gov/docs/fy24osti/86932.pdf. It deals with estimating reserves from these types of resources, but also talks a bit about general considerations, and references other good papers and demonstrations.