Pulsar was an Electron app similar to Spotlight and Raycast. It will no longer work because it relies on cloud services that are no longer online.
The config directory contains Electron data, but it also has some files that directly affect Pulsar. theme.css is loaded into Pulsar and can be used for custom theming, and api will override the default API origin, which is useful for development. credentials.json contains the credentials for the Pulsar client.