Will I be able to restore the wallet with electrum on MacOS or Windows or should I necessary reuse a Linux version of Electrum ?
I agree with 3 posts above,
but if you want to save and use a wallet file to restore it, there is a different location that you can find specifically on another OS.
On Windows - Users\AppData\Roaming\Electrum\wallets
On Mac Os - (shift+cmd+G) and ~/.electrum
On Linux - Home folder, ~/.electrum
Then, when you want to restore, in step 2, choose and select a wallet folder where you save it.
It's easier to use the save backup command in the file menu of electrum.