Kiosk Apps on Chrome Store no longer work - kiosk-mode

Question

We have developed a number of kiosk (Chromebook) applications and published them in the Chrome store. Any of our existing ones can be updated and continue to work and are available on the manage kiosk applications screen. You can type in the code on a Chromebook which does not have them and they will be installed.
But ever since the Windows/Mac change which blocks apps on those platforms - when we create a new kiosk app (even if we use the exact same code as before) they no longer will install. If you go into Chrome extensions on the Chromebook you can add them there. But if you go into Manage Kiosk Apps and then type in the code or the URL you get "Invalid Application" as the message. Note that the application is published as UNLISTED not private (same as the ones which work).
We have also used the Google App Builder and used GitHub code for basic kiosk apps to test if its something in our build but it seems to be any kiosk app.
We have tried repeatedly to get help from Google to no avail. Would appreciate any assistance here.
On the off chance its our manifest:
{
"manifest_version": 2,
"name": "test",
"default_locale":"en",
"short_name": "test",
"description":"test is a kiosk app",
"version": "0.0.0.17",
"icons": {
"128": "icon_128.png"
},
"permissions": [ "clipboardWrite","power", "storage", "alarms", "notifications", "webview", "gcm", "https://*/*", "http://*/*"],
"app": {
"background": {
"scripts": ["background.js"]
}
},
"minimum_chrome_version": "46",
"kiosk_enabled" : true,
"kiosk_only" : true
}

Answer 1

ref: https://bugs.chromium.org/p/chromium/issues/detail?id=870300&q=component%3AUI%3EShell%3EKiosk%20&colspec=ID%20Pri%20M%20Stars%20ReleaseBlock%20Component%20Status%20Owner%20Summary%20OS%20Modified
If your Chromebook, Chromebase, or Chromebox is from 2017 or later, it
won't work in kiosk mode unless it's managed by an administrator.
So you have to pay a $10 fee per station or similar to enroll a device into Google management and then you force publish an app to run in kiosk mode. Licenses are acquired from Google partners who presumably can discount in bulk or something, idk.
For comparison commercial TVs for display signage run WebKit or Chromium browser and can be run on closed networks with no subscriptions required. Primary vendors being Samsung and LG. If you visit any of the signage CMS vendors you will find in their support documentation that a device management subscriptions is mandatory (example: Signage Live).