bitcoin core – How safe it is to store keys in Electrum? I think Luke Dash JR didn’t recommend it

I agree with Luke Dash Jr and in general this wiki with the fact that doing anything without a full node is a mistake:

https://en.bitcoin.it/wiki/Clearing_Up_Misconceptions_About_Full_Nodes

But my question was in terms of just storing the keys in the Electrum wallet format to use in an offline gapped computer to sign the transactions and then broadcast on other full node computer online. Im just paranoid about the whole seed model. I reckon reading something to do with key derivation where if an attacker knew a private key of only one of your addresses and something else, they could somehow know subsequent addresses. Something to do with key derivation or something. I think this has something to do with it.

https://bitcointalk.org/index.php?topic=5265935.0

Im so paranoid to use anything but wallet.dat Bitcoin Core format that im not sure if missing on the clear advantage that being able to “spawn” your wallet anywhere in the world by remembering 12 words delivers, however, im concerned that you give away on security by using this. Why Bitcoin Core does not give you this method of wallet of knowing 12 words and being able to spawn your wallet if there were no tradeoffs?