Global Entry Appointments

Has anyone had success in booking an appointment for global entry recently in the greater Houston area? My boyfriend’s application has been open for over a year now because of COVID, and he can’t find an appointment. He keeps checking the website multiple times a month, but no appointments in the area are available. The closest appointment available is 5+ hours away.

Is there a location for walk-ins, or a better way to nab an appointment? (For example, a time of day to check the website or a number to call?) His application expires in June, so he’s searching for more details on how to get an appointment.