I have option #5 and it’s saved me a few times over the course of the past 10 years. Reliable, inexpensive system.
We have sumps on both ends of our house. Now that the surrounding lots and lawns are in place they run quite infrequently. Although past performance doesn’t necessarily predict future results, in almost twenty years I can count on both hands the number of times we lost it but longest we’ve been without electricity is five minutes.
With that (and expecting intermittent run [rather than constant draw]) in mind, we have two identical pumps in each hole. The backup pumps are plugged into Jackery portable power stations. They’ll automatically switch to battery without power and should provide several hours of coverage with the bonus of being able to use them elsewhere if needed.
Plus you can add more auto type batteries for longer run time to cover power outages. Cheapest, simplest option. So cheap you can have a back up set up just in case first one fails.