Passport applications are almost always a genealogy gold mine. We frequently find confirmation of birthdates, home addresses and even photos of the applicant.
They have helped me find family members on numerous occasions. Of course, finding one for a family member is a long shot because the window of time they cover is fairly narrow and is even farther narrowed by the fact that few people could afford to travel and thus had no need for one.
The three passport applications of Jesse Tirrell are a good typical example. There isn’t a photo but there is a lot of ‘great information about him.