In coinos go to settings (tap the hamburger menu to get to it).

In settings, look for nostr

In nostr, tap + new connection

Choose your settings (name it SN or something, set a budget and routing fee and renewal period if you like)

Then tap submit

You should now see this connection. Tap copy NWC

In SN -> settings -> wallets tap add wallet

Tap coinos and then select add send capability

Paste the NWC string from coinos (should be in your clipboard from when you tapped copy NWC

Tap test to see if it is working.

Sometimes Coinos goes down. You can check out Rizful as another custodial alternative. More or less same steps: look for the NWC string and paste it into the send capability area for Rizful wallet in SN wallet selection.