Last year as part of my K8s journey I started training for the Certified Kubernetes Administrator (CKA) certification. It is an online, proctored, performance-based test that requires solving multiple issues from a command line.
And after learning and training using the Certified Kubernetes Administrator (CKA) with Practice Tests course by Mumshad Mannambeth I successfully passed the exam. The exam itself was not as hard as I've expected, but you really profit doing the training beforehand getting your K8s skills fostered. I can totally recommend the course and the certification!