There’s always nushell. It’s fairly new, not quite to 1.0 yet (0.96.1 at time of writing), but the constant breaking changes seemed to have stopped. It hits all your points and it’s quite fun to use when writing scripts. Bonus that it’s also pretty much tailor-made to manipulate data.

For Matrix, I’d recommend conduit over synapse, with the expectation that all of synapse’s features haven’t yet been added (most notably support for spaces, which may or may not be a dealbreaker).

It’s incredibly easy to set-up and very lightweight. I never self-hosted synapse due to how resource-heavy it is, and constantly had issues with dendrite racking up resources as well.conduit has honestly been the easiest thing I’ve self-hosted.