Is it possible to run a REST API with a worker?

import { Hono } from "hono";
import { logger } from "hono/logger";
import { prettyJSON } from "hono/pretty-json";
import { cors } from "hono/cors";
//
import connectDB from "./config/db";
import { Users } from "./routes";
import { errorHandler, notFound } from "./middlewares";

// Initialize the Hono app
const app = new Hono().basePath("/api/v1");


// Config MongoDB
connectDB();

// Initialize middlewares
app.use("*", logger(), prettyJSON());

// Cors
app.use(
  "*",
  cors({
    origin: "*",
    allowMethods: ["GET", "POST", "PUT", "DELETE", "OPTIONS"],
  })
);

// Home Route
app.get("/", (c) => c.text("Welcome to the API!"));

// User Routes
app.route("/users", Users);

// Error Handler
app.onError((err, c) => {
  const error = errorHandler(c);
  return error;
});

// Not Found Handler
app.notFound((c) => {
  const error = notFound(c);
  return error;
});

const port = 8000;

export default {
  port,
  fetch: app.fetch,
};

import * as mongoose from 'mongoose'

const connectDB = async () => {
  try {
    if (MONGO_URI !== undefined) {
    //I've tried to do vars several ways as follows
    // Appears to be valid code in the sense that resolves to my string
      const conn = await mongoose.connect(MONGO_URI, {
    //IIRC this complains that $ is undefied
      const conn = await mongoose.connect(${env.MONGO_URI}, {
    //This throws an error that env is undefied, and no mwater what i've tried in the entry i can't get it to pass
     const conn = await mongoose.connect(`${env.MONGO_URI}`, {
        autoIndex: true,
      })

      console.log(`MongoDB Connected: ${conn.connection.host}`)
      console.log(MONGO_URI)
    }
  } catch (err: any) {
    console.error(`Error: ${err.message}`)
    process.exit(1)
  }
}

export default connectDB