@st0rk Hello,
I used the API V2 that I shared above for getting purchase order data via HTTP connector in Power Automate. In my case I used this method instead of standard get records (BC) action because I needed system IDs for the records.
If you use standard Create a Record (v3/v2) action for BC you may not see the fields that you expect to see. There should be custom api created for this type of need then you can select the custom API in related BC action in Power Automate.
Although I don't know exactly what you want to do, the workaround can be using HTTP action in Power Automate to POST/GET from BC.
I hope it is helpful. I am BC Functional Consultant and interested in Power Automate. I'm not an expert at Power Automate but If you have further question I'd be glad to answer.
Have a nice day.