How to populate attribute value in a data extension source to a Mobile Push custom key?

I am using a data extension as a data source for a Mobile Push Inbox message type. In order to filter and categorize the subscribers, the app side would need to receive the value stored in a field (AccountID) in that DE source.

So I was attempting to personalize value in a Mobile Push custom key so the app side can use the information from there.

I tried to put AMPscript to the PN custom key:

%%[set @ContactKey = AttributeValue("AccountID")]%% %%=v(@ContactKey)=%%

Or

%%AccountID%%

Both ways don't work at all.

Later, when I checked in the Push send API. I realized we cannot specify the custom key value for each subscriber but the custom key value would be used for the whole send. So maybe we cannot personalize in the PN custom key.

Question: since I am not going to make a loop to pull Subscriber Key, AccountID and execute the push send for each record so I wonder if we have a better way to let the app side can receive the AccountID value for each subscriber or to see whether if I am missing something?