In my house, the natural gas header is directly above the staircase to the attic in the garage. I have one unused port on the header. I've been thinking about it as well. It is simple enough to run flex line across the attic to the lanai and put on a shut-off the same as the other installed lines. There are flex hookup lines from there to your appliances. The install is no different than hooking up a water heater or stove.
here is a 70' yellow flex for under $100
Amazon.com