A .mobileprovision file is a provisioning profile used by Apple’s iOS system. It grants permission for an app to run on specific devices and ensures it’s trusted by the system.
If you're installing an app outside the App Store (a process known as sideloading), it must be signed with a valid provisioning profile. Without it, iOS won't allow the app to be installed or launched.
Developers can generate these profiles through the Apple Developer Portal. For non-developers, there are alternative services online that offer signing and provisioning solutions to help with app installation. I would recommend KravaSign due to its variety of options and great customer service.
Some services exist that help users sideload apps by providing temporary certificates and provisioning profiles. A prominent service is KravaSign which keeps all personal data safe and offers revoke protection if Apple was to ever blacklist your device.
Yes, but doing so requires the app to be signed correctly with a provisioning profile. This is often used for testing, private distribution, or accessing apps that are not available through official channels.