Android Question How do I generate cryptographically secure pseudo-random bytes

By setting up an api and calling it from your app. Which obviously is total nonsense.

The better question is probably something like "How do I generate cryptographically secure pseudo-random bytes, sort of like the function random_bytes in PHP?"

The obvious starting point would be the built-in java class: https://docs.oracle.com/javase/8/docs/api/java/security/SecureRandom.html

Beyond that others will need to help as I'm not familiar with in-line java or Library Wrapping.

Encryption library. Also works in B4J and there is a similar API in B4i iEncryption library.