Thanks.
I hope is not too off-topic but regarding "Custom Word extensions" to the seed phrase.
How does this work? Because i guess that if i try to import a seed phrase to another wallet, let's say "BitcoinCore" i don't think they will support the extension of custom words i added to my seed phrase?
The extension word is a password that together with the electrum seed phrase will create a new completely unique wallet that is only accessible with the seed phrase + custom word which is also known as a Passphrase, each wallet gives a name to it , but the technical term is Passphrase (salt).
Electrum generates seed phrases different from the BIP39 standard, so only Electrum and some wallets like Sparrow wallet and bluewallet provide support for the electrum seed phrase standard.
Bitcoin core works differently in relation to wallet generation, it follows the BIP32 standard which generates a seed, but the seed does not encode BIP39 words, Bitcoin core uses descriptors.
If you want, you can import the same electrum wallet or a BIP39 wallet with or without passphrase via descriptor. You must import using the wallet's xpriv, knowing xpriv it is possible to import into Bitcoin core.