Smokeydope is your username. That can't be changed due to how federation works.
But your display name is SmokeyDope. Display names can be changed to anything as much as you want.
No? But it can be implemented. Though I don't think anyone really cares about it, so most likely it won't. Revolt does not even advertise itself as a gaming chat platform, but just a chat platform.
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.
Threads is trying to become that. We have a list of instances blocking Threads here: https://fedipact.veganism.social/