I will make this my first ever Lemmy post:
Overall, this definitely feels like a promising alternative with some growing pains. The bigger communities are decently active but the decentralized nature of Lemmy carries the risk of some communities becoming too fragmented where communities are duplicated in different instances. As some other users have suggested, This could be remedied by creating "Super communities" spanning the Fediverse which could help with growing to a scale large enough to rival Reddit and incentivise even more Redditors to make the switch.
20 year old me would see that as an opportunity for an epic Harold & Kumar inspired road trip.