Basically as the title says. We have semi frequent power outages where I live. The noise machine in my daughter’s room goes out and wakes her up. If I were to buy a USB powered one, plug it into a power bank like one of those 10000ma ones you get for charging cell phones, would it have continuous power. Basically like a cheap UPS
I personally use an APC pro 1500 and it will run my (admittedly large) network for an hour. If your router and modem are around 50 watts you could probably get about two hours.
If you need anything longer than that you should look at solar generators that have an UPS mode like from what bluetti or ecoflow offers as they are a significantly better value than a purpose built high capacity UPS with the added benefits of being able to hook up portable solar panels to extend the run time even further.
Hey forgot to say thanks a ton for this info! I’ll be pulling the trigger on one of these soon.