How do I implement custom ServiceMonitors to scrape metrics from applications?

import * as pulumi from "@pulumi/pulumi";
import * as k8s from "@pulumi/kubernetes";

// Create a namespace for monitoring resources
const monitoringNamespace = new k8s.core.v1.Namespace("monitoring", {
    metadata: { name: "monitoring" }
});

// Deploy the Prometheus Operator
const prometheusOperator = new k8s.helm.v3.Chart("prometheus-operator", {
    chart: "kube-prometheus-stack",
    version: "34.10.0",
    fetchOpts: {
        repo: "https://prometheus-community.github.io/helm-charts"
    },
    namespace: monitoringNamespace.metadata.name
});

// Define a sample application service
const appNamespace = new k8s.core.v1.Namespace("app", {
    metadata: { name: "app" }
});

const appService = new k8s.core.v1.Service("app-service", {
    metadata: {
        namespace: appNamespace.metadata.name,
        labels: { app: "my-app" }
    },
    spec: {
        selector: { app: "my-app" },
        ports: [{ port: 80, targetPort: 8080 }]
    }
});

// Define a ServiceMonitor to scrape metrics from the sample application
const serviceMonitor = new k8s.apiextensions.CustomResource("app-service-monitor", {
    apiVersion: "monitoring.coreos.com/v1",
    kind: "ServiceMonitor",
    metadata: {
        namespace: monitoringNamespace.metadata.name,
        labels: { release: "prometheus" }
    },
    spec: {
        selector: {
            matchLabels: { app: "my-app" }
        },
        endpoints: [{
            port: "http",
            interval: "30s"
        }]
    }
}, { dependsOn: prometheusOperator });

export const monitoringNamespaceName = monitoringNamespace.metadata.name;
export const appNamespaceName = appNamespace.metadata.name;
export const appServiceName = appService.metadata.name;
export const serviceMonitorName = serviceMonitor.metadata.name;