Iframe throws and error "refused to connect". Gatsby hosted website needs to be called inside the iframe from another website

Intent: we are using Gatsby development framework and Gatsby as a hosting platform.
It is a migration project from SPA to Jamstack architecture. Static pages using SSG and it has been completed. just started SSR and it will take some time to dev & release. meantime client suggested to use iframe from existing website(SPA) and load the Gatsby site.

Prior to implement the solution I have tested in the below online solution. It throws an error “refused to connect”.

Attempt # 1:

  1. Installed “gatsby-plugin-netlify”: “^5.1.0”
  2. Add the below in the “gatsby-config.js”
    headers: {
    “/*”: [
    “X-XSS-Protection: 1; mode=block”,
    “X-Content-Type-Options: nosniff”,
    “Referrer-Policy: same-origin”,
    Content-Security-Policy: frame-ancestors 'self' https://seleniumbase.io/,

Is this is the right approach?. Can someone please advise on this?. Thanks

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