"A Dictionary of English Place Names" by A.D. Mills (Oxford) gives:-
"Pyon, Canon & Kings, Heref. & Worcs. Pionie 1086 DB (=Domesday Book) Pyone canonicorum 1221. King's Pyon 1285.
'Island infested with gnats or other insects.' OE (Old English) pie (genitive plural peona) + ëg"
The Distinguishing affix 'Canon' derives from early possession by the Canons of Hereford.
In other sources, ëg is translated as 'land between streams', rather than 'island' - c.f. "Place Names of Derbyshire" and derivation of Eyam, from the dative plural ëgum.