Is Strider Hiryu manga considered as canon? After playing Strider on PS3, and using Strider Hiryu across all Marvel vs Capcom games, I have become aware that he, like most game characters, have manga that delve into his past and life in his world outside the game. 

Are these manga considered canon? Or are the games the only canon materials?
Yes, the Strider Hiryu manga is canon.

The manga series was created by the artist group, Moto Kikaku, in collaboration with Capcom. Since Capcom is credited with the game's creation, the collaboration result with the creator is considered canon.

The manga was serialized from May to October 1988, while the first Strider Hiryu game, Strider (CPS-1) was released in March 1989.
The manga serves as an origins story of the lead character Hiryu.

Source: Strider Wikia