The first inteview is online just asking background and what have you delivered a related project in the past or challenges of complicated and relevant projects in the past. It's always helpful to have a PM who has a good knowledge of the technical matter, but it's often not necessary for them to be a SME. Often when leading technical projects, my first job is to rapidly educate myself about the technical matter enough to be effective as a PM but not nearly to the level of the tech experts.