The client/server ecosystem in XMPP is going strong. Fragmentation is no more of an issue in XMPP than any other open ecosystem. That's not to say it's easy to prevent things being fragmented in an open ecosystem, but it's something we try to stay on top of.
For example, for some time now the XMPP Standards Foundation annually publishes the "compliance suites" which detail for developers what up-to-date implementations are expected to be supporting. We recently updated the xmpp.org website to automatically calculate and display the compliance status of every project.
Monal's support for calls is in alpha builds, and they're hoping to release it in the coming months. Gajim (written in Python) is looking for someone to help them out with their audio/video call stack, which needs some attention.
For example, for some time now the XMPP Standards Foundation annually publishes the "compliance suites" which detail for developers what up-to-date implementations are expected to be supporting. We recently updated the xmpp.org website to automatically calculate and display the compliance status of every project.
This, for example, is not fragmentation: https://matthewwild.co.uk/uploads/screenshot-20230119-167413...
Monal's support for calls is in alpha builds, and they're hoping to release it in the coming months. Gajim (written in Python) is looking for someone to help them out with their audio/video call stack, which needs some attention.
Servers (as in, actual deployments) are monitored via https://compliance.conversations.im/ - which feeds into curated lists such as https://providers.xmpp.net/