There's also this site, which gives you more options for filtering, but also seems to throw up errors pretty consistently in my experience.

https://defed.xyz/

In terms of figuring out which instances are cool with one another, this site is also quite useful. It's a web of trust model that a majority of major instances participate in.

It shows which instances endorse one another, with those instances obviously being federated. It also shows how instances choose to describe/tag themselves, which can give you a better understanding of their general vibe. And it also shows which instances are viewed with suspicion, as they are hesitated or censured by other instances.

@Martineski pinging you