How to update functions and apps in azure managed application

Question

We have developed an azure managed application. The managed application is using custom providers, offering end-to-end solutions (api, ...) as azure app service, functions.

Besides the arm templates, the application contains azure functions and azure app services.

The initial deploy is using the marketplace definition itself and initial webdeploy is done through arm template, which works fine.

However, as a publisher, we want to update the functions and apps afterwards (update).

Using devops/deploy is not allowed using our users that where assigned to the managed application as owner. Stating SCM is not running.

Are there people who already have got this working? FTP works fine, but we would rather want to use webdeploy.