I received a number of requests on my discord server for help with development of a closed-source application with this exact feature set a few days before you posted this. (Update: Seemingly unrelated)
In case this is related (update: seemingly not - was someone else with unfortunate timing), I would like to give a reminder that Lightning Launcher's license does not allow for any portion of its code to be used or redistributed, even if modified, without attribution.
Requesting access to the user's filesystem is also a strange choice. The same functionality can be achieved without sensitive permissions by using a system file picker. You're welcome to reference Lightning Launcher's implementation of a similar feature, which does not require file system access.