imported piper + PROTON_VOICE_FILES changes
This is interesting.
I assume they mean this Piper: "A fast, local neural text to speech system that sounds great and is optimized for the Raspberry Pi 4." A recent Proton Experimental changelog entry seems to suggest that it is.
For those unfamiliar with it, Piper does some of the best speech synthesis I've ever heard. You can listen to samples here, and if you're willing to install 60+ MiB voice data files into your browser, you can try it here.
I don't know how many games use speech synth, but I often use game-related tools that would benefit from this. For example, my Mumble client tells me when someone joins voice chat, and reads me any text that they write, so I don't have to take my eyes off the game. Having a human-sounding voice instead of a robot voice would be nice.