Who is the app for?

It is clearest to break it down by task rather than by profession.

Developers and testers — to reproduce location-based scenarios without going on site. A bug that shows up at a specific point in a city becomes a repeatable run from your desk: a set of reference points is saved in favorites, synced between the website and test devices and called up with one tap. A separate walkthrough with a checklist is in the article about testing location.

Those who do not want to share their exact address. Some apps ask for location without a real need, and denying access breaks them entirely. Spoofing gives a third option between “give my exact address” and “do not use the app”: share the district or city instead of the apartment.

Those who need another region. Seeing maps, schedules, local listings and prices the way a resident of another city sees them is a scenario where spoofing misleads no one.

It is better to say up front who the app will not suit. It will not help where a service reads the “mock source” flag and refuses to work with substituted coordinates: banking apps, delivery confirmation, corporate time tracking, games with anti-cheat systems. This is not a flaw but a consequence of the app working strictly within Android's built-in mechanism and not hiding the fact of spoofing.

And it does not replace a VPN. A VPN changes where your network traffic comes from; spoofing changes the coordinates the system gives to apps. An app that determines location by IP address will not notice spoofed coordinates, and an app that asks the system for coordinates will not notice a VPN. Sometimes you need both — see the article location spoofing or VPN for examples.