But you can derive the master private key itself from electrums seed (with several code snippets available on github), which then is compatible with most wallets.
there is a much better way of getting the master private/public key from the Electrum seed phrase that keeps you secure while avoiding possible bugs in those third party codes.
- remove the wallet password if you have any (Wallet > Password > enter previous pass and remove new one as empty)
- open the wallet location in explorer
- open wallet file in a text editor
- search for xprv (it is under "keystore") copy that!
- remember to re-encrypt the wallet file