Is it possible to compile iRules into a binary/encrypted format for distribution as an app?

An iApp is a way to package a configuration, but does not in and of itself prevent tampering with the included iRule(s). You cannot compile an iRule yourself. You can certainly obfuscate, encode, and/or encrypt portions of an iRule, but given that the iRule processor needs to be able to access the underlying code, you would have to also provide the de-obfuscation, decoding, and/or decrypting functions with that iRule.