I did not, but I will. I would just point out that Privastead assumes the the push notification infrastructure is untrusted anyway.

Sure, just wanted to tell you about it, as this seems to be defacto standard for foss android apps, for example most if not all https://matrix.org clients use it for push notifications (when you use their de googled build, or don't have play services) available. I also use a Signal fork with UnifiedPush and have some server alert scripts which post to my self-hosted ntfy instance, and the ntfy app itself will display them (otherwise for the Messengers, the Notifications will be from the messenger app itself, as these apps get "notified" aboout a notification and then do their own thing).

it's not about trusted/untrusted as in what will they do with the data. it's entirely about will the service be available long term or if theGoogs will deprecate it in the future.

I have no skin in the game of push notification infrastructure, but we've seen plenty of ShowHNs where a critical part of the Show is a total dependency on a 3rd party shim. While this isn't something like a dependency on a Twitter API that suddenly got yanked, it is still something that devs should really consider. Especially given theGoogs' track record.

Maybe this isn't the case it is a library deeply embedded in the Android ecosystem, but anytime a ShowHN mentions a dependency on theGoog it sets of the SpideySenses