In the new Android Firefox (Fenix), you can cycle between tabs by swiping horizontally over the URL bar. So, it behaves similar to Ctrl+Tab and Ctrl+Shift+Tab on the desktop.
Just found this out by fat-fingering and it’s really useful to me, so I figured, I should share.
Hmm, I am on Nightly and I kind of feel like I might have stumbled upon this earlier, if it would’ve already been in there for a long time, so definitely possible…