Stop! Honestly, if you don't understand why using 127.0.0.1 (locahost) won't work, then you need to get some proper help.
This is going to involve opening your firewall. If you do that wrong, you'll have more problems than connecting Metabase.
This is a strange way to connect your local to your cloud instance I would say.
However, should you wish to continue, you could use a tunnel to e.g ngrok.
The tunnel will give you a URL that you can then use on metabase.
I haven't tested this myself, so all of this is theoretical. Here is a link that can help:
Another option might be to deploy a metabase instance on your local machine using Docker for example. This solves all the headache of proxying or tunnel.