The file sensor should be able to read any local file into a sensor. A good example could be a local .json file. But unfortunately the file sensor only reads the last line opposite to it’s name, indicating that it reads a file. This mean that you can’t load a local .json file. unless you have minified it to become an unreadable one-liner.
Only reading the last line seems like symptoms treatment for people who cant use templates to pass the file content. It feels like the File sensor is not a generic file sensor but a sensor specifically for reading a log file with a certain format.
The file sensor should read the entire file or at least have a configuration option to do so.