The single biggest obstacle you will face is . Many modern or commercial games, and even some newer firmware files, encrypt their .pac archives to prevent tampering. The tools mentioned above, such as the basic PacExtractor for visual novels, explicitly state that they "can't extract encrypted data yet". When you encounter encryption, your extraction attempts will simply fail.
A second payload. Inside a string that looked like a comment— // TODO: remove debug —the APK flagged a base64 blob. Decoded, it was a shell command: pac file extractor apk exclusive