Switching from In-App to SKExternalLinkAccount

We are a digital newspaper that has an iOS app that uses Apple's InAppPurchases to manage/buy digital subscriptions

iOS15 enabled the SKExternalLinkAccount https://developer.apple.com/support/reader-apps/

we would like to switch to external link, however using the request form https://developer.apple.com/contact/request/external-link-account/

the Does your app offer in-app purchases? must be No in order to request however, we currently use the InApp, but would like to disable it and switch to External Link, is it still possible?

What would the transition look like in regards to our existing customers?