OpenPush seems to be a FOSS alternative to Google's Firebase Cloud Message (FCM) framework for push notifications:
https://bubu1.eu/openpush
https://f-droid.org/en/2020/02/03/openpush-talk.html
Although there don't yet seem to be any OpenPush servers running, will it be considered?
Yes, at least for the F-Droid version of the app :)
Not the Google Play version?
Not the Google Play version?
it doesn't matter much, when you have Google Play installed, since you most likely already using Google Push servers for other purposes. When you using F-Droid, you may not have GMS stuff from Google even available.
openPush is still in early development phase, but let's link at least list of applications considering or being packaged on F-Droid or elsewhere needing openPush support [1]
Most helpful comment
Yes, at least for the F-Droid version of the app :)