Tabletop.js was a great way to take a Google Spreadsheet and makes it easily accessible through JavaScript. Google has shut down the infrastructure that Tabletop relies on.
It doesn't seem possible anymore to load the data directly from a Sheet into the browser via JavaScript.
One workaround seems to be prepending 'https://cors-anywhere.herokuapp.com/' to the Google URL. However, that server is only provided to easily and quickly try out CORS Anywhere. And at this time I don't want to host my own instance of CORS Anywhere.
Another workaround seems to be using a server to download the data and save it somewhere more easily accessible. So we're going to use a GitHub Actions workflow (run daily), to fetch the data from a collection of Google Sheets and save it to a GitHub repository.