Hungary, before its conversion, already recieved much influence from HRE and Italy : it's worth noting that for being acknowledged as king, he asked for support from the emperor and/or the pope, and that his son was re-established by them.
Eventually, it was more structurally dependent from Latin Christian entities than Byzantium.
You'd then need to have enough butterflies to deal with that, making Hungarians less favoured by Imperials and more close to Byzantium, including geographically.
So, it may be a bit of cheat, but what about having Magyars fixing themselves in Carpathian/Danubian region instead of Pannonia, either by their first settlement, or by being pushed back by HRE?
If you really want an Orthodox Hungary, as with understood in the limits of IOTL, that's going to be far more tricky. It's possible, but I wonder how much it would be akin to Rus' church. I would bet more on a mixed Hungarian church, using Greek rites but eventually swithing its obediance to Rome (as a modern Greek Catholic Church) quickly enough.
Let's say Samuel Aba keeps firm on the Hungarian throne, and decide to swith to Greek rites to differenciate himself from Peter.
But you'd definitely need to screw up the HRE to prevent him to intervene and reduce Samuel to obedience (and, eventually, to reduce him in small bloody pieces)
