How to pass dynamic environment variables to SvelteKit run with Express?

[simonsarris]

The adapter-node docs detail both how to pass environment variables, and how to use Express to handle a SvelteKit build, but suggest no way to do both these things together. Is there an easy way to do that?

Running an express server, the express script can see everything:

import express from 'express';
import 'dotenv/config';
console.log(process.env); // works

But in a given server.ts that express is serving, these won't work:

// Both of these would be undefined
import { env as priv } from '$env/dynamic/private';
import { env as pub } from '$env/dynamic/public';

Of course env/static would still work, since they're baked in at build time, but not dynamic.