A propane generator will not buy you much time or output.
If the home owner has natural gas? They should could get a natural gas generator, that way they have a continuous supply of fuel if the grid fails.
Grid and gas failure? That happens only after a significant event, like a major earthquake. Not much you can do about those sorts of events. ( The person lives in Ohio… so not as much concern. )
Cost-wise? They would be better with a dual fuel system for heating. They live in Ohio, they probably have AC so moving to dual fuel when the AC system needs to be replaced is the smarter option.
A friend of mine just got a generac generator, fully installed it was 17k. Pretty steep, not to mention the gas bill with any significant outage will be huge.
This was my biggest takeaway from Japan in terms of home design - the bathroom design. At a small apartment in Tokyo the "bathroom" was in fact three separate spaces: a nook where the washer and sink lived which opened into the living room, one side of the nook featured the toilet closet, the other, and actual bathroom with tub and shower. This lets three people use the plumbing fixtures - toilet, shower/bath and sink. Though not all of the places I stayed at split the sink and bathroom.
Contrast this with the all-in-one design where a person taking a shower monopolizes all the plumbing fixtures even while they are not using them. I was on a bachelor party trip with 8 guys and two bathrooms where some inconsiderate people camped out in the shower for 20 minutes while people waking up had to pee so badly they went outside in the bushes. Meanwhile on a trip to Japan with five people we could easily share one or two split bathrooms and never had an issue.
Oh, and the electric bidet is a clear winner in terms of bathroom accessory to buy. Less TP use and no threat of swamp ass that demands you take a shower. Heated seat in winter is a blessing, especially in the morning. After my Japan trip it was the first thing I bought when I got back home.
Trees are wonderful for a number of reasons, and the need for them for local climate, which includes shading and their contribution to local humidity, is important as well.
They are not, though, a significant sequestration for CO₂.
A helpful way to think about this is to consider coal. To produce coal the energy input comes from time, pressure, etc over tens to thousands of millions of years.
The significance of trees is for the local climate, or global if you are considering one of handful of rainforests.