..... is there a way to create a "symbiosis" of the Electrum wallet and Bitcoin Core (or something like that), so that to sign transactions safely on ANY(doesn't matter which Linux distro, or even Windows) ALWAYS offline system, and afterwards actually broadcasting it with one's own Bitcoin Core full node.
Before I started my full node I had been doing it easily, comfortably and safely with the Electrum wallet.
All this reduces to is generating transactions off line and then inputting them into a computer with a wallet such as Bitcoin Core.
Hooking Electrum into one end and hooking "full node" into the other is two levels of specificity without any tangible benefit.