The site is solid, but as somebody who has also built a foreign language partial translation extension over a decade ago, there's a TON of competition in this a

The site is solid, but as somebody who has also built a foreign language partial translation extension over a decade ago, there's a TON of competition in this area. Off the top of my head, I can think of Langulearn, Language Immersion for Chrome, Polyglot, Alpharabius, Mind the Word, Gloss (I think defunct now though), and Toucan. These are all extension-based approaches and range from individual words to entire sentences.