If you are managing site designs and scripts in your tenant, you may find this Powerapp useful. I built this to make it easier for our internal team to update these without needing to use Powershell or custom code.
The Powerapp uses Flow and the Send HTTP to SharePoint action to call the REST API's for managing scripts. You can add scripts to a design including adding new scripts, delete scripts and designs and add and update designs.
Things to note:
You need to be a SharePoint Administrator role to call these API's
There is no error handling except you will see the Flow fails
You need to create a blob storage to put the uploaded image as the Add picture control does not have a DataURI format
Images are added to Site Assets in SharePoint root
You need to update the settings to your blob storage location
Some User Experience updates needed to make it easier to use