I agree with the other poster. It's much more practical to add a second
battery-backup pump. They aren't that expensive (maybe $200 tops) and then
you have double protection -- both if power fails, and if the main pump
fails.

I added a "basement watchdog" pump several years back, after I had a very
near flood during a brief (2 hour) power outage during a major rainstorm in
a particurly rainy fall... (sump was just topping over the edge when the
power came back on -- I was bailing like mad but no way could I keep up...)

Standard pumps use way too much power for standard UPS's, which are made for
computers that take hardly any power.

My pump is supposed to be able to run constantly for 24 hours on battery...
No UPS is gonna give you that...

-Tim