Hello, electronic noob here

You may or may not know that EU plugs can be inserted into the socket in 2 ways. This means the live and neutral can be on either wire. I want to know if there is a device or circuit that can separate the live and neutral and always output them on the same wire.

(https://www.aliexpress.com/item/32957289394.html) This power meter can supposedly only function if the live wire is inserted in port 4 and the neutral in port 3, but since a EU plug can be reversed this is obviously a problem.

I've attached an images to illustrate the issue. Purple is either live or neutral. "M" is the magical device that separates live and neutral. "P" is the power meter

 

I think this is only possible if 'M' has an earth connection as well.

 

Why are you using a 100A meter for measuring power from a standard mains outlet?

Assume one wire is "hot" and one is "neutral", and then connect the meter properly including the current transformer, to those arbitrarily labeled points.
Then, without a connection to earth common, the meter then won't be able to tell which way the plug is connected (and neither can you).
Adding a polarity correcting circuit is unneeded.

 

Why are you using a 100A meter for measuring power from a standard mains outlet?

How do you know he is using 100A version when there is also 20A version available?