ntfy credentials support?

[shaohme]

The ntfy (https://ntfy.sh/) server implements authentication and ACLs to secure its push messages.
Matrix Synapse homeserver currently supports it well, but without authentication.

The ntfy configuration (https://docs.ntfy.sh/config/?h=access#access-control-list-acl) manual states that administrator could allow anonymous (everyone/) to have write access to "up*" topics while having auth-default-access: "deny-all" to mitigate this problem.

A user expressed this issue at binwiederhier/ntfy#1034

Have synapse developers considered this issue, like allowing configured credentials for ntfy server, or should this problem be addressed otherwise, like the Element X client announcing to synapse which credentials synapse should use to notify with?

Maybe this is a non-issue for most people. I just got curious ...