Mozilla has recently officially released their long running project that gives you the ability to translate webpages in a private way done entirely locally using machine learning. Nothing is transmitted anywhere, browser does all the translations entirely locally. It will download some support data and then perform translation locally on your system.
Here is a quick example of Mozilla Firefox 102 rendering German eBay (ebay.de) webpage and translating it into English on the fly…
It has a limited range of supported languages, but it supports all the major European ones and more are coming in the future.
You can download Firefox Translations extension here: