Mostly, yeah.
But some communities in instances that haven't been accessed by anyone from your own yet won't show up iirc (shouldn't be much of an issue on popular instances).
And the ones that do - only show the number of subscribers from your own instance, and not the overall count. For now at least.
You can use lemmyverse.net to search across all instances and see the total sub count. I hope this gets integrated into Lemmy itself at some point.
Also, try wefwef.app, Connect for Lemmy, and Liftoff for Lemmy; they're also great.