Tab groups have become one of Firefox’s most loved ways to stay organized — over 18 million people have used the feature since it launched earlier this year. Since then, we’ve been listening closely to feedback from the Mozilla Connect community to make this long-awaited feature even more helpful.
Yeah those settings you want exist. Look here:
When I go to that link there is a red muted sound icon in the upper right corner:
That button takes you here: https://lichess.org/faq#autoplay
That page explains that I should enable autoplay audio to hear the sound on the page.