I'm tried both the apk from the Protonmail website as well as the one from Aurora Store.

Notifications are switched on within the app and are enabled in Grapheneos. However, I'm not getting any notifications when new mail arrives.

Notifications work for other apps. From my understanding, the Proton Mail app doesn't need Google Framework to allow for notifications so I'm not sure what I'm missing.

    Callahan42 From my understanding, the Proton Mail app doesn't need Google Framework to allow for notifications so I'm not sure what I'm missing.

    Your understanding would be incorrect, I'm afraid.

      Ha! Joke's on me then!

      So is there an official way to get the notifications to fire? I have Google Framework installed now and I'm still missing notifications.

        Callahan42 Proton Mail might need to find Play Services when first installed. So if you installed sandboxed Google Play after installing Proton Mail, try uninstalling and re-installing it.