You might sideload an Android app, or manually install its APK package, if you're using a custom version of Android that doesn't include Google's Play Store. Alternately, the app might be experimental, under development, or perhaps no longer maintained and offered by its developer. Until now, the existence of sideload-ready APKs on the web was something that seemed to be tolerated, if warned against, by Google.
This quiet standstill is being shaken up by a new feature in Google's Play Integrity API. As reported by Android Authority, developer tools to push "remediation" dialogs during sideloading debuted at Google's I/O conference in May, have begun showing up on users' phones. Sideloaders of apps from the British shop Tesco, fandom app BeyBlade X, and ChatGPT have reported "Get this app from Play" prompts, which cannot be worked around. An Android gaming handheld user encountered a similarly worded prompt from Diablo Immortal on their device three months ago.
Google's Play Integrity API is how apps have previously blocked access when loaded onto phones that are in some way modified from a stock OS with all Google Play integrations intact. Recently, a popular two-factor authentication app blocked access on rooted phones, including the security-minded GrapheneOS. Apps can call the Play Integrity API and get back an "integrity verdict," relaying if the phone has a "trustworthy" software environment, has Google Play Protect enabled, and passes other software checks.
Graphene has questioned the veracity of Google's Integrity API and SafetyNet Attestation systems, recommending instead standard Android hardware attestation. Rahman notes that apps do not have to take an all-or-nothing approach to integrity checking. Rather than block installation entirely, apps could call on the API only during sensitive actions, issuing a warning there. But not having a Play Store connection can also deprive developers of metrics, allow for installation on incompatible devices (and resulting bad reviews), and, of course, open the door to paid app piracy.
I used it as my daily phone for months, and... well, I'm willing to deal with the problems. Without pretty careful battery management it's not feasible, and it's hard to manage your battery given the glitches. I often found my phone dead after a couple hours because it woke the screen immediately after I locked it because... reasons, and then kept it awake until the battery died. The biggest issue aside stuff like that (small issues that cause big problems), the biggest issue was I couldn't get a map app working. There are some distros with working maps, none for my phone. Also call quality was horrendous. Like. I'm known for being able to tolerate bad quality, but this was, at times, about as bad as I remember my firefly phone being when I was 12, and I could not feasibly understand people at times with that thing.
But the only reason I stopped using it was because the wifi isn't working on it. Once I get that back up and running I'll likely switch back to it. As bad as it can be at times, I still feel more comfortable having that as my primary phone than my Android.
Really appreciate the insight