By far the best google translation extension for firefox. The name sadly makes it quite difficult to find through mozilla.

Ive used it for meany years now and honestly a lot of the time I cant tell when im looking at a non-English website.

Its codebase is open on Github and it locally detects for non-native languages to decide when to send the page to google which puts my mind at ease not being just a huge data mineing operation for google.
read more: https://github.com/FilipePS/Traduzir-paginas-web/discussions/537.

This means it's as functional as chromes integration and yet probably a lot more private.