Someone might be able to do that if they're monitoring power usage directly on the CPU with >microsecond precision for an extended period of time, not with a power metering plug that gives a fairly inaccurate reading at the wall every second or two, after having gone through the power supply transformers, rectifiers, capacitors, and containing noise from every other component in your device.
You can exfiltrate encryption keys if you can monitor power usage.
https://www.securityweek.com/platypus-hackers-can-obtain-cry...