[progval]

Out of curiosity, what are these implementations?

[Arathorn]

matrix-js-sdk, matrix-ios-sdk, matrix-android-sdk, matrix-androidx-sdk (soon to be refactored out of riotx), matrix-nio (py3), mtx-client (c++).

In dev you also have libQuotient, metaolm and matrix-purple.

matrix-python-sdk also has support, but got replaced by matrix-nio.