The keyboard shortcut and pin button are nice additions that make me wonder why this hasn't been included as a native Firefox feature so far.

While the developer is working on adding the ability to customize the keyboard shortcut, AutoHotkey (for Windows only, or other Mac alternatives) can help with that, by making it possible to use another key combination but send Alt+P in Firefox.

By creating a more complex script, I found out that I can use AutoHotkey for a double click on a tab to send Alt+P and pin it, which takes this to another level not currently allowed for web extensions (they can't read clicks on tabs anymore).