Bridged VPN on GCP?

[x-yuri]

At the moment it looks to me like it's not possible to launch a bridged VPN on GCP. The thing I'm struggling with is replacing the main network interface with a bridge. I believe if that is possible, the rest should be easy. I tried it two ways:

• Based on the script from the docs. The details are in a gist.
• Based on the Arch Wiki article. The details are again in a gist.

Am I missing something?

Just in case, here's a Stack Overflow question with probably more info.