Hey @Lars_Hofstetter 
Welcome to the community! What exactly are you trying to update in your ecommerce store? Is it a list of products?
You should be able to pull in the collection items using the collections endpoint above to get your product and sku IDs. Using the “Pull from Webflow” step, select all of my sites
from the dropdown to return your site ID.
You can then try swapping them into this endpoint:
PATCH /sites/:site_id/products/:product_id/skus/:sku_id
Then, send this as your JSON body:
{
"fields": {
"name": "{name}"
}
}
Let me know if that helps!