He connected the phone to his laptop, signed the app with a developer certificate, and hit install.
For users on iOS 14.0–15.4.1, TrollStore allows permanent sideloading without resigning. A genuine decrypted Hollow Knight IPA can run via TrollStore. These are the “exclusive” versions that actually work. However, they still require you to find a clean decrypted IPA from a trusted source—and those are vanishingly rare. hollow knight ipa free exclusive
21+ only, please drink responsibly.