In my experiences the vast majority of websites allow it -- a select few disallow. Although that group will expand. One trick I've found is to register the 2FA

In my experiences the vast majority of websites allow it -- a select few disallow. Although that group will expand. One trick I've found is to register the 2FA with a "real" number, and then port that number to a voip service. I never use a real cell phone number for anything.