Rated 2 out of 5 stars

Why does this plugin ask for FULL access to my computer upon installation?

This review is for a previous version of the add-on (2.1.0). 

Because tbkeys-lite uses a WebExtension Experiment to capture key events. There is no WebExtension API to do this. A WebExtension Experiment has the same permissions as all legacy add-ons had in Thunderbird 68 and earlier. I have opened a ticket on Bugzilla about creating a MailExtension keyboard shortcut API here: https://bugzilla.mozilla.org/show_bug.cgi?id=1591730