Thanks to your help, I bought two power banks Proove Powerbox 60000 mAh 65W. This is not enough for heaters and large appliances, but it is definitely enough to charge smartphones and provide oxygen to aquariums!! I'm really grateful to you! especially to  canis_aureus, of course, who donated half the amount! wonderful person, how much good they have done for us! 😭💛
I hope the winter will be much easier than what the news is saying... but in any case it will be very useful!