In-fact, its simplified as:
(() => import('./index.js'))();
This allows plesk to serve pages, but unclear if the swallowing of async is indicating to Plesk that the site is ready sooner than ideally. But it's working for me.
I had exactly the same issue, resolved by adding the following (as index.cjs) to my build output and pointing plesk at that (having created a package.json with "type": "module" in the build output too):
(async () => {
await import('./index.js');
})();