I'm writing a PowerShell script to interact with our Chromebook inventory and I have followed the process outlined here
https://developers.google.com/admin-sdk/directory/v1/guides/delegation
To create a private key file and delegated it permissions.
However, there's no documentation how to decode the public/private key to generate a token without using one of the pre-built libraries, which of course don't include PowerShell. Even if there was a language agnostic description of what needs to be done I'd be able to try something out, but unfortunately there isn't.
I found this question which seems to be the same issue as what I'm having but it was never answered either.
Google Identity Platform: Using OAuth 2.0 in Powershell using Firebase Admin SDK private key