Yes, I have seen this...but sometimes the person who asks the question also finds a solution him- or herself.

HOWEVER, for any future finders of this post, I will answer this one 😉

The key is to dynamically add a (temporary) linked server to the XLSX say e.g. called TempExcelSheet

The you can then query the worksheets and columns using systems stored procedures sp_tables_ex and sp_columns_ex