I'm a privacy focused self hoster and ntfy was not good enough for me so I created Prism with an optional Android app: https://git.lonecloud.dev/lone-cloud/prism

The difference: Your phone doesn't get notifications from your notification service directly, but from Mozilla which helps to hide your digital fingerprint of you using a separate notification provider like ntfy. Prism also allows Telegram or Signal to act as a notification distributor. In addition, I use Proton Mail which doesn't really allow custom notification services. Prism has a custom integration to work around that so your proton mail notifications don't have to touch google services.