I have an SDS1104X-E due in any moment (though thinking Amazon let me down); my thanks to all the info here that helped me decide (and yes, should have gotten an X-U and saved the $100 but in absence of real knowledge I figured I might one day appreciate those extra features or ADC). Anyway...
Most of what I want to do is hunting for low voltage issues in astro gear, but...
I have a standby generator for the house and am curious how clean its output is. Now when I run it, I mostly turn off expensive electronic stuff just in case. I have a EV now also, and conceivably one day might need to charge from it (I am in hurricane prone florida) but using dirty power could be an seriously expensive mistake there.
This is NOT a question about how to test safely - please assume I can (or that I will be dead and not bother you further).

To put any even modest load on that generator I have to turn off utility power to the house (it's a panel interlock). I then have two choices to power the scope: consumer quality UPS's which are going to have a nasty square wave, or the generator itself.
I do know that the generator's RMS voltage is good, whether idle or under load. I know its frequency is 60 +/-1 from a frequency counter in prior tests. It is properly installed, grounded appropriately in coordination with the house. It is a 10k/13k-surge non-inverter generator, so my gut tells me it has a decent sine wave, but I really don't know, hence my wanting to look. I also realize there are better tools than a scope -- but none that I have access to.
My question is two pieces:
Does low quality power to the scope risk damage, e.g. a consumer grade Cyber Power UPS? My guess is no, no more than any SPS powered gear like computers.
But perhaps more importantly - Does low quality input power to the scope affect its measurements? Will I end up seeing a horrible result that is really from the input power not the measurement? Assume a solid ground throughout, will confirm or modify as needed the UPS.
I should note a third option is go buy a good sine wave output UPS, but trying to be cheap since I just splurged on the scope.
I have searched and have seen mixed answers, most simply saying "don't need a UPS", a few saying 'won't hurt it", but none seeming to authoritatively address whether it impacted the results.
Advice welcomed.
Linwood