Stephen’s dying words are in Acts, written decades later by a believer with an agenda. And “calling on the name” in 1 Corinthians 1:2 could be a formula of allegiance, not prayer.

Acts is later and its author is a believer, granted. The stronger evidence is Paul, who is earlier and firsthand. He prays to the Lord for the removal of his thorn (2 Corinthians 12:8), ends 1 Corinthians with the Aramaic prayer Maranatha (our Lord, come), and describes Christians as those who call on the name of the Lord, which in Joel 2:32, the passage he is quoting, means calling on YHWH in prayer. Allegiance and prayer are not separable here: calling on a name for salvation is what one does to God.