Angelic beings, in total communion with God, are technically "saints," even though we may not know their names.
The Church honors the archangels, Michael, Gabriel and Raphael, as “saints.” These are the only angels we know by name from the Bible, but that doesn’t mean there aren’t other angels who are saints.
Technically speaking, all angels in Heaven are saints.
The word saint is derived from the Latin word sanctus, meaning “holyone.” While it is the word we use to identify humans who have risen to holiness and now enjoy the beatific vision of Heaven, it can also be used in reference to angels, who are holy and worship God for eternity.
As a note for clarification, humans can become saints, but humans cannot become angels.
When we die, our soul is separated from our body for the moment, but will be reunited with it at the end of time. To become an angel after death would mean that we become a different being entirely.
The good news is that we can join all the angels and saints in Heaven by following Christ here on earth and doing all that we can to live out the Gospel.