Not sure if helpful or not but a new nostr:nprofile1qqst4qyeqenw7zm0fwjsty68h6cnys5jre2xd8ngqpjv5a2j26s78fspr9mhxue69uhhyetvv9ujuumwdae8gtnnda3kjctv9udlhm7y account creates an npub (and nsec of course) for you. But this is more useful if you're new to nostr (and bitcoin) in general. 

Good for onboarding someone to both the orange and purple pills in one go. 

 I want to receive npub and know payment address agnostic of client 

 If you're looking to get the lightning address of a given npub you can query nostr relays for "kind 0" events for that pubkey. kind 0 events contain the profile metadata for a given pubkey including their username, avatar, etc. It may also have a "lud16" field with their lightning address, but it's an optional field.