Where does “Ivo” come from?

Ivo (English) comes from Proto-Germanic īhwaz, from Proto-Indo-European *h₁eyHw- — yew.

Ancestry of “Ivo”, step by step

Step	Language	Word	Meaning
1	Proto-Germanic	īhwaz	yew; name of the I-rune
2	Proto-Indo-European	*h₁eyHw-	yew