This is misleading to me.  At some point you have to connect to your own node or somebody else’s to verify you received a valid transaction.  Yes once you’ve verified that you can create and sign the transaction offline and use whatever node you want to broadcast it.

ChrisS

bitcoin

Bitcoin watch-only wallet vs hardware wallet for long-term savings

chaum

If you use Electrum on TailsOS offline, why do you want to break that offline part and go online?

Don't you know how to use Electrum offline?
You just have to prepare the tx, sign it and then save the whole tx code onto a txt file on a memory stick. Then from any other  PC online with a dummy Electrum you just broadcast that tx already signed. There's not even need to connect to your own node.