This is a great example. Matrix has the concept of widgets which let you embed little webapps, which can be used as a compatibility layer for stuff like payment

This is a great example. Matrix has the concept of widgets which let you embed little webapps, which can be used as a compatibility layer for stuff like payments. For instance video conferencing is done in Matrix as a widget (Jitsi) for clients who just support widgets... but clients with native jitsi support (Element iOS and Android) integrate it natively rather than using a widget.