We certainly can add a 3-point circle command.
Do you need a circle or can you use an arc instead?
TPC does already include a 3-point arc command as shown in the attached curve fit.png file on the left. Just draw the end points of the arc (snap if you want) then drag the mouse to create the arc or snap to another point to create the arc.
If those points are in a traverse, TPC has COGO curve fitting which allows you to use any number of points to get a better fit. See https://traverse-pc.com/WebHelp/topics/horizontal-curve-fitting.htm.