What's a good alternative though? I tried Lemmy a while back and whilst FLOSS communities there were pretty active, others not so much.

Only reason I use Reddit these days is for r/sysadmin and r/SCCM, lots of useful content there that saved my bacon on multiple ocassions - especially on Patch Tuesdays. Haven't seen this sort of active userbase and content posted anywhere else.

I have Lemmy set to show best of the last 24 hours and there's always a page or two of posts. That's plenty enough for me