See, it's the entire premise that voice conferencing is needed to have a replacement for "Discord is used for documentation". It's not. Almost by definition. If anyone wants videoconferencing there's Jitsi. That's the thing I'm aiming to: you won't ever to get anyone to "replace" Discord if they have to replace all of it. Capitalism doesn't allow for that. We are trying to do better here. Splitting problems into their component and significative parts makes them much easier to solve.
The closest use case that in the case of these kinds of communities would even need videoconferencing would be something like "Discord is being used for live tech support for modchipping Switches" and for that case there's also already established alternatives... and it would be wise to not implement for that anyway.