Thanks for the valid suggestion. Your feedback is now open for the user community to upvote & comment on. This allows us to effectively prioritize your request against our existing feature backlog and also gives us insight into the potential impact of implementing the suggested feature.
Distributed transaction support for cross-instance, Managed Instance only, T-SQL and .NET distributed transactions is in public preview. Related documentation and blog links:
We invite you to provide us feedback for the public preview scope via the survey: https://aka.ms/sqlmi-dtxpublicpreview
Team is also considering options for extending the scope of support for distributed transactions. Therefore, we invite you to fill out the following online survey to provide your feedback to us: http://aka.ms/sqlmi-distributed-transactions
-Managed Instance Product Group