Ended up doing someting similar which I found here: http://help.qlik.com/en-US/sense/June2017/Subsystems/Hub/Content/Scripting/ScriptControlStatements/For%20Each.htm
Here is the example I ended up with:
sub GetAllExcelSheets (Root)
for each Ext in 'xlsx'
for each File in filelist (Root&'\*.' &Ext)
FROM ['$(File)'](ooxml, embedded labels, header is 2 lines); // specific header according to my example, could be different for yours.
// for each Dir in dirlist (Root&'\*' )
// call DoDir (Dir)
// next Dir
call GetAllExcelSheets ('lib://(LibName)')