Hey! We are using the Update Reminder for the org. And it works flawlessly. Also we have disabled "Switch to Classic" button for most of the profiles (i.e. moved to Lightning). The link in the reminder -- View Details, takes us to the report. By default it is opened in Classic. So, let's say Admins could see it. But not for those who have classic turned off. Is it possible to customize the button and change link to the same report, but in Lightning?
Had the same request today and did some investigation. Here's what I found:
When Update Reminder is enabled, the "View Detail" button in the reminder email sends users to the Report Home page, not a specific report. This is an out-of-the-box function and can't be changed. But you can paste URLs for your key reports and dashboards directly into the email message body.
https://help.salesforce.com/s/articleView?id=sales.considerations_for_scheduling_reminders_to_update_opportunities.htm&type=5