what are some alternative that one can use for rds postgresql and sqs?
SQS: There's AWS MQ, which is based on ActiveMQ and supports AMQP. If you're going with a more CNCF-focused stack and want to use NATS, I'm not aware of any hosted options.
You would just want to stay away from Aurora specific features like the one in OP.
Replicating it on a different platform could also be fine with a combination of logical and physical backups.