I think it would be nice for the people who want the option.

However, Lemmy and other “message board” types of applications/services don’t really register to me as something that needs immediate acting upon. If someone replies to a comment of mine, I don’t think (or hope, at least) they would expect me to reply back in say five minutes. I do get an email notification, which my email app is set to check for new emails every 45 minutes.

The exception I could see to this is for moderation actions - if someone reports a comment/post for example, or someone signs up for my instance (though I could see that being a bit annoying on larger instances where someone could be signing up say every 5 minutes), that would be nice to get instantly.

That is something that I really like Android’s “Notification Channels” for. If an app implements it properly, you’d be able to receive push notifications for just moderation actions, and leave it turned off for comment replies.

I (personally) do not find push notifications to be addicting so-to-speak, but I do use a wearable so that the things I do find important to have push notifications on for (such as messages from family) I can see/“feel” those come in instantly.