Introduction
Following Messenger's designation as a core platform service of Meta in September 5th, 2023 they had six months before the DMA's obligations come into force. Once that happens, Meta should publish the terms and conditions for interoperability, and any reasonable request by a messaging service for interoperability should be met with the technical interface being made operational within 3 months, free of charge. Interop requirements for some messaging features (group chats, voice&video calls) don't come into force at the March deadline.
According to some, however, gatekeepers may not do enough, or if they are technically compliant, they may implement the necessary changes in a purposefully ineffectual manner.
Criteria
Chat feature milestones will resolve YES, if they are actually operational with any specific third party service. Meta publishing an API and ToS, but no services taking the offer will not be considered hitting the milestone.
3rd party milestones will resolve YES, if a listed feature can be used symmetrically between Messenger and the 3rd party. Chat feature milestones (as well as 3rd party milestones) may be added, if there is interest. I will not bet on 3rd party milestones.
"Group chats" only refers to sending messages. It does not refer to creating or managing groups.
@traders Messenger got a 6 month extension to comply with interop reqs, it seems. https://ec.europa.eu/commission/presscorner/detail/en/IP_24_1689