Converting ZIP to IPA is usually not a "transcoding" process (like converting MP3 to WAV). It is simply an extraction process. The IPA file is likely inside the ZIP, or the ZIP is the IPA with the wrong file extension.
For those building apps, the standard way to generate a functional IPA is through Product > Destination > Any iOS Device Product > Archive Distribute App wizard to export the archive as an IPA file. sign an IPA so it can actually be installed on your device? convert zip to ipa work
Attempting to bypass these for piracy or unauthorized distribution violates Apple’s policies and may be illegal in your jurisdiction. Converting ZIP to IPA is usually not a