Superbacked is a company selling you a backup service for small secrets. They offer a fair amount of features that are no doubt well thought through, albeit closed-source. As their user, you put some trust in the company, their product, and the expectation that they will still exist in a few years time, when you need to recover your secret.
Hyperbacked removes a few of these drawbacks by virtue of being open-source. It's easier (but not necessarily easy) to understand. It's probably easier to use than psst, although power users would want to set up an airgapped computer...
Psst, in contrast, is a humble open-source repo, giving you a PDF that you can fully understand and inspect, with no additional dependencies. I hope it's fun to use. It might even help some people with backing up secrets :)