Customer-owned modem activation WITHOUT using a phone or an app

What is the procedure for registering a customer purchased and owned cable modem without using a smartphone in any way ?  I do not own a smartphone, and without a working, registered and activated modem, I have NO internet connectivity.  Does Xfinity still use a "walled garden" website (ie. the old style "xfinity.com/activate" site) as an option to activate and register a new customer owned modem ?