Would such need to use smaller denomination units (smaller than satoshi) require a hard fork? Can someone shed some light into it?
For adding more decimal places, we have to change the consensus rules and a hard fork would be required.
According to consensus rules, the amount field in a bitcoin transaction must be an integer between 0 and 2100000000000000 and we can't send 0.1 satoshi or 0.01 satoshi.