“People could be refused the new permit even if they have a valid passport.” https://www.birminghammail.co.uk/travel/british-holidaymakers-could-refused-new-27504884
“Under the entry/exit system, every British traveller to the Schengen area must be finger-printed and provide a facial biometric.” https://www.independent.co.uk/travel/news-and-advice/brexit-border-etias-dover-eurostar-b2130495.html