google app engine - What is the best approch to setup custom domain with static IP for AppEngine

Question

I had done an investigation on below

1. Adding custom domain through AppEngine settings - Doesn't seem to be static IP, it uses Google NS.
2. Setting up VM and run as a proxy - Seems to be convoluted method and security/maintenance overhead.
3. HTTPS load balancer with internet NEG I am still investigating and it said

You should do this when you want to serve content from an origin that is hosted outside of Google Cloud, and you want your external HTTP(S) load balancer to be the frontend.

Any suggesions/thoughts for this solution will be greatly appricated to chose right solution for this

Answer 1

Waitting for answers