I've been using this project as a way to play with tech I don't typically use day-to-day in my paid work.
It's gone through a bunch of iterations. It started almost entirely on AWS serverless services (Lambda, Dynamo, etc). That ended up being ridiculously expensive for this use case, so now it's a boring Go app on a cheap VPS talking to Postgres.
The mobile app has also gone through some iterations, starting as a wrapper around a web app (CapacitorJS), and is now using React Native instead.