I don't think there is. The closest thing you have is the graph API (https://docs.observium.org/graph_api/). You could add a new API based on this one that returns the raw data for the graph instead.

From: observium <observium-bounces@observium.org> on behalf of Farshid Abediny via observium <observium@observium.org>
Sent: Saturday, January 11, 2020 2:40:35 AM
To: Observium Network Observation System
Cc: Farshid Abediny
Subject: [Observium] read RRD by API

Hello,

Is there any way to read RRD file and extract data about total bytes from graphs?

Thank you.