i imagine you won’t have an issue with spam in signal considering the .## they add to every username.
But in general the more distinct it is the less likely you’ll have someone nagging you.
If you want to avoid building a footprint of similar usernames my favorite is just switching out some letters (o’s to u’s or a’s to e’s stuff like that) or taking out specific letters entirely (ex: ottr)
like everyone else has said hardware level encryption doesn’t seem like the most sound option.
Personally i’ve just encrypted sensitive files with picocrypt, only just started looking into better encryption techniques though so there’s probably better alternatives.
How’s the Pi 3? I was considering the idea of getting one to avoid the crazy prices for newer models