"Smartphones with a 6.3-inch display are already considered compact by today's standards."
Today's standards are that every phone is big. 6.3 is not compact by any standrada. Past or today's.
This phone is extreme on other side. 5-5.5 inch would be awesome. If it'd cost 150$-ish it will sell like hot cakes. Is beyond me that nobody gets that almost nobody wants compact flagships. That's why they will never sell. Someone who wants flagship will want in 90% big screen too. Most people who buys entry level, or mid level will buy compact phones like crazy. (Almost) Nobody will buy 800-1000$ small phones...