Gazelle headset bearings

Hi guys. Just helping my 82yo dad get his e-bike back on the road. It’s a ~10 year old Gazelle Comfort electric C7+. Quill stem and loose/cage headset bearings that have totally fallen to bits with no evidence of ever having seen any grease 😂

All I’m trying to find out is what the replacement bearings are, if they are sone standard bearing I can get at a bearing shop, and even better if there is a sealed bearing conversion kit.

Thanks in advance.