Hi. I would love to get notifications on GrapheneOS without any Google Play Services etc. or any MicroG or equivalent. (For ProtonMail)

I have seen posts that indicate that the Proton team is aware of this, and wanted to implement it (and has on their other apps) but is there any way to either tell them that this is desired, or make a poll or something?

I self host several things including ntfy, so is there any way to use that for notifications? Does Proton Mail have an API that I could use to programmatically send notifications?