Using remote.getGlobal variables in modern isolated renderer process Electron

Question

I'm updating an entire app written a few years ago using Electron v1.8.8. As far as I know, Electron changed its paradigm and now the default expected way of communicating between the main and renderer process is using a module in the middle named preload.js.
To get/set global variables in the old way you would first require the remote module:

var { remote } = require('electron');

And then getting/setting it like so:

remote.getGlobal('sharedObj').get('user')

I've been trying to expose an api object in preload.js to achieve the same old functionality, but with no success.
How I would achieve this without setting nodeIntegration: true, contextIsolation: false?