If you need to prepare for Black Swan events, doesn't it make sense to have your own channel to distribute APKs to all devices? Why would you rely on the Play Store at all?
that’s a lot of tooling to build for a single application—plus not everyone is tech savvy and installing from non-standard locations requires more user support
A 100K-sized company is going to have a BYOD or corporate device issuance program with tie-in to MDM, which effectively functions as a private appstore (the DPC (device policy controller) (itself an app) can silently install apps (as in, download APK from $anywhere, hand to PackageManager) without confirmation, etc).
MDM infra is big bu$ine$$, but DPCs are quite simple to write.
(Psst. They also let you read CPU usage on Android 7+ (sadly not per task, but at least with per-core granularity). The catch? Installing a DPC requires a factory reset. xD)
> A 100K-sized company is going to have a BYOD or corporate device issuance program
Some will, some might run a more open org, with a lot of rather independent contractors, focusing on providing services on standard platforms (email, chat, wiki, bugtracker etc).
Not every device is under MDM in a big corp. Often you have people like external consultants bringing their own devices, who need to participate in (semi-)internal communications. You cannot just MDM those and you cannot just issue bigcorp devices to them, so you need something like the normal appstore to distribute the software. Maybe you even have BYOD for internal people, so MDM could be hairy from a GDPR/employee rights/liability standpoint. And maybe you even have customers and partners who you want to communicate with, whom you have to provide with a viable option of communicating. You can (maybe) separate those into an internal and an external communication tool. But then you just have two different tools, one of which will have the exact same problem about needing installation via commonly available appstores.