Good news! Next release of Fennec browser will support UnifiedPush. And IronFox plan to do it as well!
You'll be able to receive push notifications for many more apps if you're not using Play services, thanks to web apps.
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Once again, thanks to @nlnet for giving the opportunity to work on this subject.
You can give feedback for your tests with different web apps on codeberg: https://codeberg.org/UnifiedPush/wishlist/issues/27
