The bit I'm conceptually stuck on (not know much at all about how a good plugin architecture would work) is how a plugin can surface or affect the UI, especially in an ecosystem with multiple UIs/Apps/Frontends, and, a federated ecosystem at that.
Given the apps, I figure it's not possible without a convention of plugins providing APIs which apps can then implement against when available, which adds a good amount of complexity but should be viable for popular/useful plugins. Though, tangentially, this does affirm for me that the whole native mobile app expectation is a bit of a trap for a social system like the fedi (as webUIs are naturally more universal and maleable).
So, for immediate results, I can see only two options:
a plugin operates on the backend directly manipulating or creating content not unlike a bot
a plugin provides its own webUI which is made available through a simple and dedicated location in the UI
Is there something I'm missing about how a plugin system could work?