Gliders are not permitted to operate in IMC in Australia, not sure about NZ. Usually there is limited space in the panel for extra instruments anyway. Also, limited electrical power available due to having no in-flight charging system. Gliders generally run 1 or 2 small ( 7Ah or so ) batteries. Gliders don’t normally fly in poor weather and a prudent pilot won’t get in a situation like we see in the video. Robert. Glider pilot since 1972, GA since 1984.