I figured out a work around by digesting the DOM. Telerik probably won't like what I did but it works:

Register the below javascript:

window.stockChartInterop = {
    initNavigatorListener: function(dotNetReference, containerId){
const container = document.getElementById(containerId);
        if(!container)return;


        if(container._stockChartMouseUpHandler){
            container.removeEventListener("mouseup", container._stockChartMouseUpHandler);
        }const mouseUpHandler = ()=>{

            const chartElement = container.querySelector(".k-chart");
            setTimeout(()=>{if(categoryAxis[0] && categoryAxis[0].min !== undefined && categoryAxis[0].max !== undefined){
                    dotNetReference.invokeMethodAsync('OnNavigatorRangeChange', 
                        categoryAxis[0].min, 
                        categoryAxis[0].max
                    );
                }}, 100);
        };

        container._stockChartMouseUpHandler = mouseUpHandler;
        container.addEventListener("mouseup", mouseUpHandler);

    }};
After your chart renders:
await _jsRuntime.InvokeVoidAsync("stockChartInterop.initNavigatorListener", _componentRef, "chart-container");
Then wrap your chart in <div id="chart-container">
  
        
Then add:
    [JSInvokable]
    public void OnNavigatorRangeChange(DateTime from, DateTime to)
    {
        // This fires whenever the user zooms or drags the navigator
        Console.WriteLine($"New Range: {from} to {to}");
    }