I have an app that helps managing apps:
https://play.google.com/store/apps/details?id=com.lb.app_manager
And found there is an app that lets you see a list of all purchased apps, so I tried to find how it's done, so that I can do it too:
https://stackoverflow.com/q/49620194/878126
https://stackoverflow.com/q/46050134/878126
I was so interested in such an API that I've set a huge bounty, because I could't find anything about it in the docs.
Later I was sadly told it's not official, and is actually forbidden.

* Which Developer Preview build are you using? See Settings > About phone > Build number (for example OPP5.170921.005).
PPP1.180208.014

* Is this a regression from O to P?
I think it probably occurs on all Android versions.

* What device are you using? (for example, Pixel XL)
Pixel 2

* What are the steps to reproduce the problem? (Please provide the minimal reproducible test case.)
1. Install the next app and select the Google account it shows you in its dialog:
https://play.google.com/store/apps/details?id=com.azefsw.purchasedapps

* Issue Category e.g. Framework (platform), NDK (platform), Hardware (CPU, GPU, Sensor, Camera), ART (platform), Runtime Permissions etc
Security

* What was the expected result?
As I was told, this is a security flaw that was exploited.
So, it shouldn't be possible without the user granting a permission, to get a list of purchased apps.

* Can you provide the API document where this expected behavior is explained?
No.

* What was the actual result?
This app is capable of doing so nevertheless.

Please, if there is such an API, present it to everyone. And if there is no API, please do consider having it. It can be useful.
Of course, if there is any permission that's needed to be granted manually by the user, present it.