Import Google Calendar using auth token

I know there have been several questions about importing Google Calendar, but I think my problem is different. At least, after hours of searching, I didn’t see anybody else with the same problem.

The problem is that I do not own the calendar. I therefore cannot access the private .ics link in Google’s “Integrate calendar” tab. I only have the “Public URL”.

When I try to use the public URL, I get a 401 error:

Request is missing required authentication credential. Expected OAuth 2 access token, login cookie or other valid authentication credential. See https://developers.google.com/identity/sign-in/web/devconsole-project.

It seems that using some kind of auth token would get around this issue. This is exactly what GNOME Evolution does. The public URL works fine there because they provide an auth cookie or similar. They use a slightly different URL to the public URL (https://apidata.googleusercontent.com/caldav/v2/...%40group.calendar.google.com/events/), but it’s in the same vein.

I don’t suppose there is any way to get Nextcloud to include an auth token with the request? I thought maybe the auth token could go in the url, but I don’t see this documented anywhere.

Thank you for any assistance. I must say I absolutely love Nextcloud. I just wish Google played better (or that I didn’t have to use it).