The way to lower attacks would be to have the "full node" NOT online all the time as a full node, which in and of itself invites attacks. Open ports and all that.
As for the offline machine, those methods are well documented at least for legacy Bitcoin.
But why not use a Trezor or other such hardware device? Certainly they qualify as very low hassle, high security and "off line."
Electrum offline (cold storage) scheme is easy, reliable, simple and free!
Personally, I live in the poor, miserable, totalitarian country of Belarus, it is pretty expensive for me to buy any hardware, given the very high customs duties including.
Besides, it's turned out trezors may be very weak and vulnerable as well, the famous history here:
https://www.wired.com/story/i-forgot-my-pin-an-epic-tale-of-losing-dollar30000-in-bitcoin