HI @grt_fi,

It's absolutely possible to call a Microsoft flow from Nintex flow.

The Microsoft article Calling Microsoft Flow from your application | Power Automate Blog will guide you to create a Microsoft flow that would be triggered by HTTP request.

Once you save the flow you get the URL to call with the query parameters.

The payload should be the one you based on the schema below:

You could use then the Call web service action within the Nintex Flow as shown below:

It's one option you can implement. 

 Hope that helps. ^^

Excellent reply by @cecilia-penha !

But if you are less in a hurry with your process and you have a desire for overview and control, here is another alternative to consider.

I often use flow where NWC doesn't offer the functionality. I use the best of both. It makes sense as they are two completely different products with different objectives. Flow also cannot do things NWC can do...

In order to have more control I use a SharePoint list in the middle.

Example:

The process is simple:

1. Create a new item in a simple list named OrdersForFlow. The list has a field named Status that is set to Start.



2. The flow triggers on a new or update list item with the trigger condition Status = Start. When the flow completes it updates the status into Completed.



3. In the meantime, the workflow polls the status field every minute until it is completed.

Just as a simple example.

Advantages:

• Better overview of what is happening



• Manual restart of the flow by simply changing the status field into Start.



• The wait cycle can be as advanced as you like it:
  
  
  
  
  
  • Sends a message to the workflow moderator if waiting takes too long.
  
  
  
  • If the flow would start with updating the status into In Progress, the workflow could retry (Status = Start) after a really long time automatically.
  
  
  
  • etc.
  
  
  
  
  
  

BTW You can also use this the other way around: Let flow launch a NWC workflow via a SharePoint list and wait for a result. 

Just another option to consider.