A push service akin to Pushbullet - preferable through the Proton Pass extension.

Pushbullet is a service that allows users to copy links or text (or even files) from one device to another, so long as pushbullet is installed on the devices. It is minimum effort - data sent from one device can be opened (if a link) or copied (if text) with one button.

An example use case is having a message drafted on your computer, but you want to send it over to your phone and copy-paste it into some other app. Or, you are reading a link on your browser and want the link on your phone to either share, or open.

Pushbullet is also less commonly used for moving around files quickly (ex. getting a PDF to your phone, to read there).

I suggest this because Proton Pass is likely installed on various devices of a user - phone, computer, and would be a credible candidate to securely "push" a small amount of data to another device.