Where does “*hwat” come from?

*hwat (Germanic) comes from Proto-Indo-European kʷód, from Proto-Indo-European kʷós — who.

Ancestry of “*hwat”, step by step

Step	Language	Word	Meaning
1	Proto-Indo-European	kʷód	what
2	Proto-Indo-European	kʷós	who

*hwat — Etymology, Origin & Word History | Etymology Explorer