Looks a bit like https://github.com/typicode/lowdb, which I've used for a few production-ish usecases in the past.

Specifically for storing the results/state of a set of manually-executed management scripts. The scripts needed to query the data from previous executions, do some stuff, and store the output. Think poor mans version of terraform.

Everything was dumped in a git repo that was shared across a few people. It was a quick and dirty solution to manage some alpha customers before the "real" system came online.

Maybe similar to things like json-server (mockup a REST api by making a few json files) which is useful during the development process?

It's probably useful for single-user scenarios (like an Electron app) where you only need to save a minimal amount of user data.