Hashing only works if the website stores their passwords correctly. If a single website you use doesn’t hash passwords correctly, and gets their database leaked, then your passwords will all be leaked. Changing a few characters per site may help a bit, but it shouldn’t be relied on.
Also, if you’re worried about the host shutting down, you should try bitwarden. It’s completely open source, and you can self host it if you want.
The us has 3 energy grids: east coast, west coast, and texas. As long as don’t live in Texas, you shouldn’t have issues with electricity.