I built an open source and free encryption app called PreCloud, it can encrypt texts and files, before uploading them to the cloud.
Play store: https://play.google.com/store/apps/details?id=com.precloud
App store: https://apps.apple.com/us/app/precloud/id1638793841
Would you consider to include it to the "File Encryption" section?
Nice creation. Your tool + filen could be a powerful combination.