Everybody's Google results are different these days. They put you in a bubble. Hence, saying "if you Google you should see result X or Y" isn't necessarily true.

I would say for acronyms containing 2, 3, 4 letters these are all going to be taken at this point.

What matters is how much do the acronyms overlap. Pepsi (food & drink) has nothing to do with PDF editors (tech).

pEp (or p≡p) [1] on Android is a nice K-9 fork with material design and GPG support / opportunistic encryption. Its not very well known though.

Worst would've been if there's a PEP directly related to PDF.

[1] https://www.pep.security