The unforgivable sin is impenitence at the point of death.
Here’s what the bible says.
Jesus Christ called the Holy Spirit “Spirit of Truth” (John 14:17;[19] 15:26;[20] John 16:13)[21] and warned us, “All manner of sin and blasphemy shall be forgiven unto men; but the blasphemy against the Holy Spirit shall not be forgiven unto men” (Matthew 12:31).[22]
All other sin can be forgiven if the sinner becomes penitent. We don’t know what’s in a person’s heart when they die/commit suicide. Only God does. That’s why are are not to judge other’s eternal destination. We are not God.