Is there a way to implement IfNull/Coalesce in DynamoDB PartiQL?

Question

DynamoDB PartiQL does not support an equivalent IFNULL/COALESCE built-in function yet (even though COALESCE is a reserved keyword and DynamoDB's sibling QLDB seems to support it with its PartiQL implementation, so it appears to be theoretically possible). Using only PartiQL, is there any way to construct an equivalent of SQL's,

SELECT COALESCE(col1, col2) FROM sometable;

with the functions/syntax currently supported?