Welcome to the community @Anna_Kelian 
The attachments are in Beta, you can request to partecipate in this post:
https://connect.superhuman.com/t/beta-attachments/18693/
A similiar discussion was made here:
https://connect.superhuman.com/t/links-to-local-files/17700
I have in mind some really interesting concept that could benefit from the type of integrations you desire, let’s wait for an official answer from @superhumans