@weirdnemo Sorry for my delay, this extension is simply called "swipe-back" and is available on the Chrome Web Store since Opera is a Chromium-based browser. Here is the link below! It works greatly for me on all my Windows computers, enabling both previous and next swipe functionality like Chrome. Hope this helps you!
https://chrome.google.com/webstore/detail/swipe-back/mkkcgajcpakpfjgikmekgnihlbhliodo