Based on your other replies in the thread, you've resolved the issue already. Google misrepresents the feature you enabled as a security feature when what it actually does is disallowing any device or...
If you want to make your app your app easily available outside of the Play Store, you can apply to publish it via Accrescent which is a Play Store alternative available in the GrapheneOS App Store. It's currently in Alpha and you need to apply to publish apps through it. See https://accrescent.app/ for more information.
Your app is easily available to GrapheneOS users regardless especially now that you fixed the Play Integrity API store listing issue but you can support an alternative.
Your app is easily available to GrapheneOS users regardless especially now that you fixed the Play Integrity API store listing issue but you can support an alternative.
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