No. You are right in that regard. But does that mean Jesus is God?
Why didnt St. Stephen say that he saw Jesus standing at the right hand of the Father, instead of "at the right hand of God? Did Stephen see that Jesus was separate to God? We don’t know.
One could make an argument though I think: As we know, in the Trinitarian belief, all Persons of the Trinity fully possess the nature of God, they do not share it. Each owns that nature fully. Therefore each Person can be called “God”.
So, if the Father is “God”, Stephen could have meant that He saw Jesus (God) at the right hand of the Father (God), and he doesnt call Jesus God so he doesnt confuse the audience. Sorry if Im confusing you. But thats the only way I can see that Luke meant that Stephen saw God at the right hand of God.
I don’t think this is the case though, because throughout the rest of Acts Jesus is not called “God” anywhere else. I could be wrong though, Im no bible expert.
I don’t think Luke knew Jesus was God. I can’t recall any situation in Luke (Gospel) or Acts when he says Jesus is God. In fact, he constantly shows Jesus praying to God.