So I've seen NetSuite documents mentioning that my Solution Partner/Partner of Record can get access to my account and it won't count towards my regular billable user count. Does anyone know how this is accomplished? Is this an external process done via email or Support case, Ive never seen it on any entity record, etc. in the UI?

It's done by email to account manager. Available for 18 months when your 1st buy Netsuite for implementation purpose.

There is a specific license type you need added called a "NetSuite Partner Cloud Service User." It isn't free, but is at a much lower rate than a regular user license. Only one is allowed per account and the solution provider has to be identified by email. I would chat with your solution provider or NetSuite account manager about adding it to your agreement.

Thanks for the feedback! Our agreement shows that we have 4 "NetSuite Partner Cloud Service Users"... Apparently 15 is the maximum per the agreement. Not sure if Service Tier affects that.