I have a customer requesting a REST API for usage data load. Any plans to do this in the future?
Is the target MDA or Salesforce Usage Data object?  If it's SFDC Usage Data, you can find REST API documentation here:

If it's targeted towards MDA then we have documentation on Gainsight Go.  Happy to help further if there are additional questions.
Thanks Scott, this is really helpful.

For context, I'm a GS user in a customer trying to build out GET requests, rather than POST.

My aim is to allow a user to use natural language to return Gainsight info like Scorecards, usage, etc through services like slackbots or alfred 

e.g. [i]/[i]gainbot[i] what is {customer}'s score?

I note that the linked APIs relate more to creating/updating. Is there a way to use this to read the current state?
If you're doing this off of SFDC objects, then you can leverage their API and GET requests to pull down current values as long as you're looking at the right objects.  For example, current overall score is stored on the JBCXM__CustomerInfo__c object.

For non-SFDC data stored in our MDA objects, the GET requests are not supported.  Let me know if this helps, but it shouldn't be too bad to leverage SFDC APIs for Gainsight specific data that lives in Salesforce objects on our managed objects.

Thanks Scott, that gives me what I need for now.
Sounds good.  Feel free to reach back out if you end up storing data in MDA and I can discuss with you other alternatives.