Something to keep in mind is that a hotplate or inductive cooktop may not need to run at full duty cycle depending on the heat dissipation of the materials invo

Something to keep in mind is that a hotplate or inductive cooktop may not need to run at full duty cycle depending on the heat dissipation of the materials involved and the setpoint of the themrostat or temperature probe. It may be pulling its maximum rated power while it comes up to temperature, but it'll be regulated by some sort of thermostat. Once it's at temperature the rate of heat dissipation of the hob, pan, and even the ingredients themselves will affect how soon it'll drop below the threshold and power draw will resume. A system with a lower maximum power would still work, but it would be running at a higher duty cycle to maintain the same temperature. It would take longer to get to the set temperature in the first place and slower to bring it back to temperature whenever the temperature drops. That said, I'm pretty confident that 700-800 watts would be useful for many types of cooking and I think it's achievable with a dozen or so people pedaling.