The claimed "plausible deniability" benefit seems dubious. You are carrying a branded device with marketing materials that tout its ability to offer you plausibly deniability…
Plausible deniability refers to Nitrokey Storage's hidden volumes. They can optionally be setup, but no need to, and without the appropriate password it can't be distinguished. Similiar to VeraCrypt's hidden volumes.
Yes and? If you carry this on your keychain heading into a security checkpoint, expect to receive interrogation++.
It really much depends on the individual case. In a constitutional state it should make a difference if obviously an encrypted volume is used or if there is the possibility but no certainty of one, two, three or four hidden volumes.
So how long do they interrogate you before deciding there's really no hidden volume? And even if you do reveal a hidden volume, how could they ever know it's the only one? It's pointless, even if they know about the technology.
AKA never take advice from a product about evading border agents.
"This (watch|car|toupee|smartphone|encrypted USB key drive) will totally make you more attractive to potential relationship partners!"