Hi,
Please ask your question on hiding a column in IEE App10 in a technical forum in the community. Perhaps there is a way, but then it is a generic solution for the whole environment, not just HCM.
Regarding IFS Cloud, there are no limitations as I see it: you can either control who sees the data via HCM Access, or you can choose to remove the column entirely via Page Designer. Thus, you have both options.
The GDPR functionality has never been designed with the intention to hide data, that is what access is for. With the GDPR functionality you only motivate which data you are allowed to store and delete it (anonymize it) when required.
/Magnus