I’m trying to use my keyboard more since doing things with a mouse or trackpad is more time consuming. I’d like something like: pressing Control Shift Alt > to select the tab to the right (along with the current tab), and press it again to select the tab to the right of that, making it three tabs selected. Same thing with tabs to the left.
https://support.mozilla.org/en-US/kb/keyboard-shortcuts-perform-firefox-tasks-quickly
Have a peek and see if anything works for you, I doubt it does though. Wouldn’t be surprised if there is an add-on for it.