Thank you for the review and feedback.

Unfortunately, "Firefox for Android" does not support the ability to "save as PDF" through webextensions/addons -- only desktop versions of the browser support this feature.

I have added the link to the saveAsPDF API web page below that shows which browser versions support this feature:

https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/tabs/saveAsPDF

When this API is supported for Firefox on Android, the extension will add this functionality.