Hi,
how can I activate german voices in ESO? There are just german subtitle.
Stadia will pick up on the language settings of your OS. So, if you're playing on a Chromecast, open the Google Home app on your phone, pick your Chromeast, go into the settings and change its language to German. Then all games that have german synchro should be german. At least that's how it worked for me, I'm playing ESO with german voices.