Recently had an addition put onto my house, new part has a basement which has a sump pump. But doesn’t have a battery backup.

Is it possible to add a backup pump system like this ? In the same well thing or do I have to replace the whole pump for one like this which looks like a 2 in one?

Currently I’m with lemmy.world, but if i wanted to create my own, to run at my house, would I need to register a domain? I like the idea of having my own domain but also don’t know how the storage works… like if I post to my own, sure it gets stored, but if I post to somewhere on lemmy.world, where does it get stored?