How to query AWS Redshift Serverless as a Federated user via Lambda?

Question

I am trying to run queries on AWS Glue Data Catalog as a Federated user from Python script in Lambda, but I am facing the issues:

• The first issue - I cannot find appropriate way to connect as Federated user from Lambda. I only found boto3 code to connect with Redshift Serverless DB:

result = client_redshift.execute_statement(Database=database, WorkgroupName=workgroup, Sql=query_str)

• The second issue - as documentation mentioned the only way to run query on AWS Glue Data Catalog DB in Redshift Serverless is via Federated user with granted IAM Role, but when I try to grant role to my Lambda, I am getting error that Lambda role doesn't exist.

ERROR: user "IAMR:lambda-role" does not exist 

• The query that I am using to grant permission is this one - from the documentation:

GRANT USAGE ON DATABASE awsdatacatalog TO "IAMR:lambda-role";