You see spez's ban hammer coming at you.
Well well, that surprises me. But it still lacks the features.
Btw image embedding can be done using this syntax: 
It's not meant to be selfhosted.
https://github.com/revoltchat/self-hosted
it's not federated
I'll agree on that one. Though the FAQ says that it is not on their future roadmap, but is possible. https://developers.revolt.chat/faq.html
The developer seems very shady
Why?
They are undoubtedly better, but neither of them feel like Discord. They are more like WhatsApp or Signal.
Not suited for the job.
There's a new beta one which only uses its own index: https://stract.com/
And best of all it's written in Rust.
Your best bet would be to shred the data multiple times (for example with the shred command) and then break the card physically. But shredding takes time so I guess that's not very applicable to your case.
If you have a lighter, you also can try to melt the SD card's insides. That should be impossible to recover.
In any case, you should keep it encrypted all the time and only decrypt it on the fly. For example with LUKS2.
Notion mail? Wasn't that Skiff mail previously?
You can moderate remote communities, but you can't create ones. Though you can "own" (be the top mod) in one iirc.
Not using any browser that isn't open source.