[kryten]

Yes: no software, no ports, all media is tangible, no storage, hard to fingerprint (compared to say inkjets).

However there is one problem with typewriters people generally forget: you can extract everything that has been typed from used typewriter ribbons...

[ams6110]

Typewriters are trivial to fingerprint. All of them have slight imperfections in characters, spacing, alignment.

A cloth ribbon would be hard to extract anything from, I'd think, maybe you could with a brand new one. Carbon film ribbons as used in the Selectric yes, you can easily read them but they can be shredded or burned to dispose of them securely.