For more info I bought a duel fuel generator which runs on both propane and gasoline and has adapters that can tie into the natural gas meter. While not as large as Paratus, it will still run a window air conditioner, a refrigerator and some peripherals.
If it has a 220/240V out you can look into getting an external RV hookup to your breaker box. Then you can back feed portions of your house from your portable generator. The benefit there is if you have natural gas you can power your furnace and you don’t have to run extension cords everywhere.
Professional installation is recommended because they’ll install an interlock to prevent your portable generator from powering upstream of your house. Folks who jury rig it themselves run the risk of frying some poor lineman who’s trying to repair the system if they forget to open their main breaker.
Other than that besides fuel I recommend having at least enough oil on hand to do 1-2 oil changes since portables normally require them after ~24hours of continuous operations.
It also doesn’t hurt to have a spare carburetor air filter and spark plug. I ended up using all of those after the carburetor gummed and flooded the cylinder of my portable during the winter storm this year.
Also get some beefy extension cables. Guess which one of these was the lower gauge cord:
