Transaction Replication on Azure MI servers
can [Managed Instance Databases] both subscribe to Transactional Replication, and Publish, at the same time


Yes. Both publishing and subscribing are supported and you can do both, even in the same database, even on the same tables ( ie: Bi-Directional Transactional Replication).

Transactional and Snapshot replication are supported on Managed Instance.  And Managed Instance databases can both publish and subscribe, and a Managed Instance can serve as either a local or remote distributor.

Here are the main supported scenarios:


Publisher with local Distributor on a Managed Instance

Publisher with remote distributor on a Managed Instance

Publisher and distributor on-premises with a subscriber on a single, pooled, and instance database



Transactional replication with single, pooled, and instance databases in Azure SQL Database