I've been researching William Bryan(t) husband of Sarah Hardage for over 20 years. I've seen no evidence that he is Lt. Col. William Bryan and I see none here. The "sources" seem to only be online family trees. Online family trees, particularly from MyHeritage, are highly unreliable rumors.
The entire time I've been researching this family, people have been frequently, routinely slapping them together with random Bryans and Bryants simply based on a similarity in surname, without any primary evidence. That's not how genealogy works.
I will continue to look at this, and if any evidence actually supporting this connection exists, I will mention it here.
The living person who knew the most about William Bryan(t) and Sarah Hardage years ago, was their descendant Edward Freelan Bryan Jr. According to his research (which incidentally wasn't meant for publication) William Bryan was born about 1735, and William and Sarah's oldest children, Martha Isabell "Zabilla" Bryan and Mary Bryan were born about 1755 and 1758 respectively. Which means that those first two kids would have been born when Lt. Col William Bryan was about 8 years old and when he was 11.
If you care about accuracy, you should take the "Lt. Col" and date of birth away from William Bryan(t) husband of Sarah Hardage, detach him from the parents that have been baselessly given to him here, and wait until someone produces any valid evidence as to his actual parentage.
My interest in this line is that a descendant of William Bryan(t) husband of Sarah Hardage was a rather close Y-DNA match with a descendant of my 4th Great Grandfather John Bryant Sr. who lived in Fairfield Co. SC in 1785 and died in KY about 1812. Because of the Y-DNA and because both William and John lived in Fairfield at the same time (and the name William recurs in John's family) it has been thought that John and William were likely close relatives, perhaps brothers.
That's my two cent. Best wishes.