Re:Why I Actively Discourage Online Tooling like jwt.io and ...
by hundchenkatze on Wednesday September 02, 2020 @11:33AM
(#24354209)
It's not exactly what you're describing and may be overkill, but you can definitely accomplish this with Qubes OS.
The browser could recognise that tag and you get a safe space for people to copy/paste/interact with online web tools.
I'm pretty sure you can do this with WASM right now, but the browser doesn't inform the user that this is a safe space.