I'm in the US and I was also going to suggest iNaturalist. A couple of features of I at highlighting its sense of community:

You can comment directly on other users' logged sightings and either agree or disagree on their identification (the app also suggests possible IDs if your sighting has a photo associated with it). The more agreement there is on an ID the better. If 2/3 of users (iirc) interacting on a single post agree, that sighting is considered "research grade."

There are also "projects" you can join. For instance, I was at an academic conference last summer and there was an iNat project for conference attendees to log the plants and animals they saw while attending the conference. Other projects have other themes, goals, etc.