Aggregation type "last"

My use case is having an aggregated field consisting of the content type and a taxonomy.

For content type news the aggregated field hold values like this one: News

For content type publications the aggregated field has:Publications Report

I'd need to just use whatever is the last string (e.g. News, Report). I can't see a way to put these into a particular order.

Could we have an aggregation setting for last (in addition to fulltext, min, count, max, first)?

I'm happy to work on this as it seems straight forward but if you have principle objections let me know.