Even if they are not Catholic be canonized a saint in the Catholic Church?
The Catholic Church does not canonize non-Catholics. This is more a jurisdictional issue than anything. For instance, there are certainly Anglican martyrs in Heaven, but it is up to their church to canonize them, not ours.
Canonization gives us the right to assert that someone is in heaven. There’s no doctrinal reason why the Church could not make this determination for a non-Catholic, but it’s never gonna happen. This is not an injustice - the Church is under no moral or doctrinal obligation to canonize anyone.