The goals are a little different but I think it's worth pointing out ElasticMQ. I use it simulate sqs in a docker environment.
https://github.com/softwaremill/elasticmq
So far I had not problems with ElasticMQ.
I'm much intrigued by the small LOC count of SmoothMQ. When I compare it to ElasticMQ it's much smaller (probably by using sqlite's features).