There are several for climate writers and environment—I’ll post this first:

go.bsky.app/J8Ris61

And here is one for bioethics and public health ethics:

go.bsky.app/HQVYom8

I made this Disability pack, there are writers and advocates in here.
go.bsky.app/3FA2EjT

Also this Psychology, Addiction and Trauma Pack, it's just got a few people and could use more!
go.bsky.app/HukJbZ5