Not sure if this is what you're getting at, but RabbitMQ is indeed pretty great at having thousands of queues, even on modest hardware, and can be used for per-tenant queues in this way.
It does have some drawbacks though: if you have thousands of mirrored or quorum queues, managing the cluster becomes more cumbersome - it can take a while to replace nodes (rebalancing thousands of queues around). Also, the management tools (the web UI especially) don't perform that well if you have 10,000s of queues and 100,000s of consumers
It does have some drawbacks though: if you have thousands of mirrored or quorum queues, managing the cluster becomes more cumbersome - it can take a while to replace nodes (rebalancing thousands of queues around). Also, the management tools (the web UI especially) don't perform that well if you have 10,000s of queues and 100,000s of consumers