Will I be able to restore the wallet with electrum on MacOS or Windows or should I necessary reuse a Linux version of Electrum ?
Not only will the seed be compatible with other versions, regardless of the OS, but so will the wallet files. As Abdussamad mentioned the easiest way to transfer wallets from one computer to another is create backups of the wallet files, and transfer them over to the other system, and again, the OS of the two systems is inconsequential.
Baking up and restoring your wallet files is the preferred method, because any data you saved in the file will remain. For example, if you have labels set for some addresses, or if you've locked or frozen any UTXOs or addresses, all that data will be restored since that data is stored in the wallet file. If you restore your wallet via seed phrase, you'll have all your coins, but all that additional data will be lost.
But a new question arose: in what format is the electrum wallet created? In the type column, it is only indicated that this is a file. No mention of format.
It's a json file, but that's essentially a clear text file that's organized in a specific order. Electrum doesn't care what file extension is applied to the file, as long as the data is organized in json format. It could have no extension, a .txt extension, a .json extension, or make up your own. It doesn't matter.