so You think Peter meant all sins/Sin here (?)You're changing the subject. Peter gave a reason for which they were to be baptized, and it wasn't what you said.
and some Jewish believers in Jesus think it was (at least in part maybe) referring to some specific sins at that time
and it says Who he is addressing
"the family of Abraham, and those among you who fear God (ie. Gentile "God fearers")
who had been following the Pharisee teaching rather than The Way
in becoming a Believer in Messiah Jesus, Paul changed Theology from Pharisaism to The Way (the Zadok way/Biblical Judaism)
as this view suggests Peter said Jews should do
Pharisaism still rejects Jesus to this Day