Even Google's android is viable to use without Google Account. I've used a (company-issued) Sony phone for two years with in a such way, that the only account

Even Google's android is viable to use without Google Account. I've used a (company-issued) Sony phone for two years with in a such way, that the only account on the phone was for our Exchange, with built-in E-mail, Calendar, Contacts apps. Granted, the Play Store was not available, Youtube and Maps didn't work, but they were not the reason why I had that phone.