I had an online chat with an NCL agent just now (May 2024). She advised that extension leads AND power boards were OK and also provided me with a link to prohibited items (with no ".au" on the end), even though I am in Sydey 'Straya.....
Refer extract from part of the conversation :
· Are we permitted to bring a power board onto the cruise (with no surge protector)
2:24 PM
· Yes, you may bring a powerboard - however please refer to our full list of prohibited items
2:25 PM
· https://www.ncl.com/prohibited-items