Comment by andrewstuart

>> A photo revealed the chip was a NX3303X; I could not find any datasheets

Not much information out there but these are similar chips, possibly it’s a clone?

Capstone CS5213 datasheet:

https://file.elecfans.com/web2/M00/2B/BD/pYYBAGHVUbyARd_-AAU...

And also the AlgolTek AG6200 / AG6201 Series, datasheet:

https://assets.yoreparo.com/attachments/28SGHqLW2Z2MfSzEBJB4...