If avionics hadn't been a strength of the PLAAF, they wouldn't have AESA radars installed on every major surveillance and combat platform. They wouldn't have multiple institutions simultaneously developing sensors and radar systems. They wouldn't have deployed AESA radars before the Russians did.
Likewise, China is one of the few countries capable of building and testing RCS-optimized aircraft. Even though none are in service, having enough confidence in their stealth research to put out multiple prototypes is something very few can do.