It seems wise to differentiate between canonized saint and saint. We are called saints by St. Paul in many places, but notably in Rom. 1:7. I believe one may be aware of the state of his soul, through no consciousness of serious sin, and also having no attachment to sin, even though venial sins may be committed on occasion.
With personal awareness of being in the state of grace, one may be confident in saying they are one of the saints of God in the Body of Christ. If they are in danger of death while in that state of sanctifying grace, they may trust in God’s merciful love and enter heaven.
St. Therese chided a sister who was very afraid of purgatory, encouraging her to trust in God. When the sister died, she appeared to St. Therese from purgatory and said she was so right about this, and
asked St. Therese to pray for her.
If we have been the habit of obtaining plenary indulgences throughout our lives, there is a special plenary bestowed upon death that does bring us straight into heaven. Manual of Indulgences: Section 12. Praise God for His merciful love!