Social-network focused clients, are ~25. But maybe 6-7 are most used ones & some are in beta.

Algia

Amethyst

Astraea

Atlas (?)

Camelus

Coracle

Current

Damus

Gossip

Iris

More-speech

Nos

Nostter

Nostur

Nosta.me

Nostragram

Nostribe

Nostroid

Nostros

Nostrmo

Nozzle

Onosendai

Plebstr

Plasma

Primal

Rabbit

Satellite

Snort

And there are many more for things like Long-form content, chat, lists, etc. It's a wide ecosystem now