Sideloading is neither automatically safe nor automatically dangerous. The risk depends on what you install, where it came from, what permissions it requests and whether the package can be verified as the developer's intended build.
A file downloaded from the developer's official HTTPS website has a clearer chain of custody than an APK copied through a random mirror, message attachment or file-sharing host.
Attackers can repackage applications with additional code and distribute them under familiar names. The icon and filename alone do not prove authenticity.
Android applications are digitally signed. Updates normally need to be signed compatibly with the installed application, which helps prevent an unrelated party from silently replacing a legitimate app with its own package.
If Android reports that an update cannot be installed because signatures do not match, do not treat that as an inconvenience to bypass. Verify whether you have the genuine previous version and the genuine new package.
Google Play Protect is one layer of Android's app-security system and can inspect applications. No scanner is perfect, but turning protection off simply to make an unfamiliar APK install is the wrong default.
A security warning deserves investigation, particularly when the application requests accessibility, device-administration, SMS or other high-impact permissions that are unrelated to its claimed job.
A GPS tracker legitimately needs location access because location is its core function. That does not mean it should also demand unrelated permissions.
Review permissions in context: ask what feature each permission enables and whether you actually intend to use that feature.
For the practical steps, see How to install an APK on Android safely.
A short risk review catches many bad downloads. Does the website belong to the developer? Does the file name and version make sense? Is the connection HTTPS? Does the developer openly explain why the app is distributed outside Google Play? Does the app request permissions that match its advertised function?
For a GPS tracker, precise and background location can be understandable because they are central to the product. A request to read SMS messages, become the default accessibility service or gain device-administrator powers would need a separate and convincing explanation.
Finally, keep your copy of the download page or release information long enough to know where the package came from. If you later receive an update from a different domain or an unsolicited message, do not assume it is genuine just because the icon looks familiar.
For a GPS tracker, precise and background location can be understandable because location is central to the product. A request for unrelated high-impact permissions would deserve a separate and convincing explanation. Do not decide that every permission is acceptable merely because one sensitive permission is expected.
Keep using the official developer site for later releases. An update received through a message attachment, shortened URL or unrelated APK mirror should not be trusted simply because the icon and app name look familiar. Android signatures provide an important protection against an unrelated package silently replacing the genuine application.
If an update will not install because its signature differs, investigate first. Uninstalling the existing app can remove local data, including queued information that may not yet have reached the server.