Send Note to Device doesn't collect any data.
User preferences (options page data) are stored only locally and are accessible only by extension itself.

This addon is NOT using my own Cloud Server (it has no host permission, so it can't send any data). Notes are "send" (synchronized) into other devices using the browser built-in synchronization mechanism.

Notes are stored not-encrypted, but they are accessible only by the extension itself. Synchronization between devices should be encrypted in all browsers (Firefox Sync. is actually using E2E encryption, so not even they can read the data).