I only just purchased an M5Stack Faces kit this year, with the sole desire to build a firmware based on this feature (As it is shown or mentioned in all videos relating to the faces kit)). Is the engineer that wrote this no longer contactable?
It seems you have just moved onto other products and abandoned something that had promise. It feels like you have swept the whole faces kit under the rug.

Also why is the speaker and amp so bad? all firmware produces horrible noise