Done it !
Experimented with different settings, aided by Ollama
And maybe also fixed by updating the Postiz app to latest Cloudron release which was just available.
The settings I am using in env (edit in File Manager) are :
NOSTR_PRIVATE_KEY="your nsec key here"
NOSTR_RELAYS="wss://relay.damus.io, wss://relay.nostr.wtf, wss://relay.nostr.io, wss://relay.nostr.band"
# NOSTR_NIP05="" if you want your user name
EDIT : Hmmm, maybe spoke too soon.
Above settings allow me to add Nostr as a channel.
But unable to post An error occurred while posting on nostr so investigating ...
