In Transaction Details: Gas used should not be expressed in Gwei

Gas is a quantification of EVM opcode processing. It doesn't really have a unit name, but I think it can simply be "gas units". Etherscan doesn't even give it any unit name.

Gas by itself is not currency or money, so should not be expressed in currency units (e.g. wei or ETH).

Gas price is a *rate*: currency *per* unit of gas, like how much money you pay for a bit of work.
It's commonly expressed in "Gwei". To be technically correct, it should be "Gwei per gas unit".

Here is the unit conversion from Gwei to nETH:
1 Gwei
= 1 giga wei
= 10⁹ wei
= 10⁹ x 10^-18 ETH
= 10^-9 ETH
= 1 nano ETH
= 1 nETH

Network fee = Gas x Gas price

e.g.:
If
Gas used = 50,000 gas units
Gas price = 10 Gwei per gas unit
Then
Network fee = 500,000 Gwei
= 500,000 x 10^-9 ETH
= 500,000 nETH
= 0.0005 ETH