Create Azure Function to call the Yammer API and use it in Flow

I'm aware that in Microsoft Flow you can use the existing Yammer connector to login to Yammer and send messages. I know that sending praise is not currently supported but it is possible by calling the REST API. Therefore I created an Azure Function to do that and set up a connector so I could call it from Flow. This works if I provide the Azure Function with a bearer token. But is it possible to some how login to Yammer, obtain a token and pass it to the function during the Flow creation?

I don't know enough about Microsoft Azure functions to answer that part of the question. However, I know that if you have the access token for a verified admin user in a Yammer network, you can use obtain the access token of any other user in the Yammer network and impersonate them (https://developer.yammer.com/docs/impersonation). Perhaps this will help.