Acts 6:8 - Stephen is described as “full of grace” (πλήρης χάριτος)
The link below are bible translations that also stated "full of grace":
Now Stephen, full of grace and power, was performing great wonders and signs among the people. (Berean Study Bible)
New International Version
Now Stephen, a man full of God's grace and power, performed great wonders and signs among the people.
English Standard Version
And Stephen, full of grace and power, was doing great wonders and signs among the people.
And Stephen, full of grace and fortitude, did great wonders and signs among the people.
It woulds seems that most translation render (πλήρης χάριτος) is really "full of grace".
St.Luke is both the author of scriptures who described Mary was full of grace and Stephen as full of grace too. Is St.Luke describing the same attributes to Mary and Stephen, meaning sinless having the fullness of light and there's no darkness of sin, not even a stain of sin?
Only Mary was preserved immune from all stain of original sin. Stephen by virtue of Sacraments of Baptism & Confirmation can received sanctifying grace and the seven gifts of the Holy Spirit, but the stain of orginal sin remains.
What is the meaning of grace?
In Western Christian theology, grace is "the love and mercy given to us by God because God desires us to have it, not necessarily because of anything we have done to earn it"
Stephen was "full of grace" means "full of love and mercy". God is light, and since Stephen was full of grace it follows that Stephen was also "full of light". There's is no darkness or sins in the soul of Stephen.
St.Luke was describing the state of the soul of Stephen, "full of grace" means "full of light", as evident in the succeeding verse where St.Luke described the appearance of Stephen;
All those who sat in the Sanhedrin looked intently at him and saw that his face was like the face of an angel. (Acts6:15)
Angels are creatures of light, and for Stephen to be seen like an angel means the light of God was shining in his soul, there's no more darkness in his soul. Stephen had reach perfection like what St.Paul had boldly exclaimed;
Galatians 2:20 New International Version (NIV)
I have been crucified with Christ and I no longer live, but Christ lives in me. The life I now live in the body, I live by faith in the Son of God, who loved me and gave himself for me.
St.Luke is making a connection to Mary's soul in describing the soul of Stephen.
While Mary was "full of grace" by singular privilege of the immaculate conception making her sinless with no stain of sin. Stephen had perfected the call of Jesus to be perfect imitating the Heavenly Father being merciful and following the greatest commandment about love. Stephen had perfected Christ image in his soul, he was "full of love and mercy", thereby making his soul ready to enter God's Kingdom.
The face of Stephen was like an angel, his soul having no stain is worthy to enter straight into God's Kingdom.
"...Nothing defiled shall enter God's Kingdom".(Revelation21:27)
Truly, Stephen like the Blessed Virgin Mary had been a perfect disciple of Christ, and St.Luke gives honor to Stephen martyrdom proclaiming the perfect state of his pious soul.
Ave Maria, "Gratia Plena" and Stephen "Plenus Gratia". (St.Luke the Evangelist).