Reality is that vendors in this space and most niche IoT spaces do not have the resources or expertise or budget to offer support at that level, let alone define, build and monitor SLA based metrics and service delivery.
Maybe. I personally believe it is just a matter of the level of importance. Any decent developer or customer support personal will know how to obtain basic page level response time from logs. If it is hosted in someone's cloud then they have their own analytics or work books. Worse case scenario you extract the logs and use Excel. But as you noted budget and/or priority.
I always loved getting those sorts of requests from our account team(s) but alas I guess I'm preaching to the choir.