connecting external RAG to Xano

Hello,

we are building a RAG located on an external server (RAG is ChatGPT based). How do I handle the authentication between RAG and Xano? I understand I have three options:

1. API key generated in Xano

2. Json web token generated in RAG server

3. mutual TLS

Is this a right list of options? how would you think about each of them from implementation easiness vs. security point-of-view? (I would prefer to be on a safer side)

Thanks!