Schedule Performance Index (SPI) formula + S-curve charting

I am working on a project for a large product and have been asked to produce a schedule performance index (SPI) and S-curve chart that will visualize progress to schedule over time.

Definition:
“The schedule performance index (SPI) is a measure of the conformance of actual progress/earned value (EV) to the planned progress (PV)”

Formula:
SPI = EV / PV

Schedule performance is typically displayed on an S-curve chart that shows, EV, PV and Actual cost, like so:

Currently Monday has a few limitations that prevent this:

  • My attempts to create a formula to calculate SPI are successful, but the additional logic required to assess whether non-earned work is actually due yet is proving difficult
  • Should I be succesful in getting the formula to work, my ability to visualize the data into an informative chart will be highly limited without an S-Curve
    chart widget. This article indicates it is possible, but does not go into detail and I am not seeing this? https://monday.com/blog/project-management/s-curve/

In all, just wanted to request further features supporting Earned Value Management and visualization, and confirm if there are tools available I have not seen. Thanks!

Edit:
One last note, the linked article says it is possible to use “WorkOS” data to drive charting, however when I assemble charts in Monday I do not see this option. How would one do this to say set up the X axis as the full project timeline and use the Y axis to display a cumulative line such as “work completed over time”? Or do the opposite to create a “burndown” chart?