Hi, Electron maintainer here.

> I just tried this out with Slack on macOS, and it did work

Here's the thing with how gatekeeper works, that application had already passed gatekeeper and will never be _fully_ validated ever again.

If you zipped your modified Slack.app up, uploaded it to google drive, and downloaded it again. Gatekeeper would 100% reject that application, the ASAR file is included as part of the application signature. You can prove this by checking the "CodeResources" file in the apps signature.

You can't re-distribute the app without gatekeeper completely shutting you down.