I have a Honda 2200W quiet generator (exactly like
@IcSyU above) I bought for tailgating probably 2010ish. Used it EXTENSIVELY during the derecho in CR - no power for 12 days.
It was fine running the fridge and deep freeze, as well as some fans and such. You have to be a bit careful of motors starting up at once. Theoretically, that take-off surge can be a problem and go over the limit. You could def hear the generator rev when the fridge kicked in.
I think a sump pump would be the same wrt the take-off. So having 3 things all at once, you'd want to manage the take offs carefully somehow. They do make a "soft start" device, which I think is a capacitor-ish thing so the input is steady even when the draw surges. Maybe that's an answer?