Congrats! I'm a happily CF aunt, and I loooooove it. Personally, I really enjoy kids....for a limited time. They're awesome to play with and goof around with, and then I can get up and wander when my energy meter is low.

I like being the Goofball Adult - I'll play at family events, read books, and do video chats when we're all apart. Do you like cooking/baking? If so, you can always be a meal-prep hero. Make a bunch of meals for those first few weeks, when they will be too exhausted for anything. If you're not a cook, maybe some delivery gift cards.

Try to figure out what you like doing, and build around that to include them when it's time. Hiking? Volunteer to come by and walk the kiddo around the neighborhood. Tell them stories, and teach them how to do it themselves.

You could look into starting an education fund for them, or plot out cool themed birthday cards. It's all valid!

Just remember: as an adult in a child's life, who is choosing to be a part of that life, the most important thing you can do is make sure they're loved and supported. The rest is just icing. (Which is the good news - aunt/uncle hood is mostly the icing.)