As part of an implementation project I needed to call M3 APIs on the Infor MT cloud from an external system. To work through this I setup Postman per the Infor YouTube video and then got a (very) basic Powershell script working to pull information from the ION APIs.
I've written up details here if they are of use to anyone:
https://www.linkedin.com/pulse/calling-ion-apis-from-powershell-alistair-johnson/
http://movexblog.blogspot.com/2019/11/calling-ion-apis-from-powershell.html
Cheers, Al.