In my old house I had a battery powered backup on my sump pump. Then we had
a major ice storm and the water came in too fast for the battery powered
pump AND a gasoline powered pump. Got 5' of water.
I installed a second sump, a second sump pump, and put a water powered back
up on it; AND got a generator.

If that doesn't seem paranoid enough, I moved to a house where the sump pump
hadn't cycled once on 12 years.

Now for you...
I recommend a battery powered backup and a generator. I would also have a
replacement sump pump on the shelf just in case. Paranoid? Well we've
already established that; but I have doubts about any backup handling your
water for very long; so you really need to keep your main pump working. The
backup is to handle it until you get the generator working or if no one is
home, or if it breaks and you have to replace it. (I just got my basement
pumped out and my sump pump broke! Fortunately I had a spare.)
I don't like the water powered pumps I have installed; they seem like junk.
Hopefully the expensive ones are better, but I haven't seen those.