I'm sympathetic to the idea that a company is going to be better at doing backups and maintenance than I am, but for the first point: it sounds like they're using the local machine's SSH key to wrap a symmetric key[1]. Unless you're sharing the same SSH key across all of your machines, this tool probably isn't very useful when switching between computers.
Edit: It looks like they generate their own SSH key instead of using an already present one[2]. So you'd presumably need to copy that to each machine that you'd want to use so that it can unwrap the real (cloud-stored) decryption key.
Edit: It looks like they generate their own SSH key instead of using an already present one[2]. So you'd presumably need to copy that to each machine that you'd want to use so that it can unwrap the real (cloud-stored) decryption key.
[1]: https://github.com/charmbracelet/charm#how-it-works
[2]: https://github.com/charmbracelet/charm/blob/master/keygen/ke...