Get organisational GSuite addon for Gmail in Gmail iOS app

I've got a GSuite add-on, which is privately available for our GSuite organisation. It works as intended on desktop, but somehow I'm unable to get it to show up on the Gmail (iOS) app like our domain-wide installed "Slack for Gmail" does. I've tried:

1. Finding out if I need special properties in my appscripts.json, nothing to be found about this.
2. Instead of installing it as a individual app, install it domain-wide (like our Slack app). No results.

Only thing I can think of that would be an issue is that our app is a organisational private app. Might that be the problem? I'm lost...

Unfortunately, only enterprise-level organizations (with well established and trusted platforms - who probably have special agreements with both Google and Apple) are able to deploy their add-ons so that they are accessible via iOS.

The rest of us are bound by a number of restrictions (with very limited mobile support for GSuite add-ons). See documentation.

Maybe the heads of your company can approach Google and/or Apple directly to work something out.