File Type Validation plugin for FilePond
https://pqina.nl/filepond/docs/patterns/plugins/file-validate-type/
The File Type Validation plugin handles blocking of files that are of the wrong type. When creating a FilePond instance based on a input type file, this plugin will automatically interpret the accept attribute value.
If you're having trouble setting the correct mime type, use this codepend demo to view the mime type detected by different browsers.