you can use custom online available js or c# libraries for this tasks. E.g. I can recommend 'sheetjs'. Basically you create an Action that starts are filepicker. Then get the file object of the file picker, use sheetjs online samples to read the excel content and then process the data.
I actually thinking about making my own Excel import tool open-source (or at least share it with people who also want to contribute to the project). It´s a comparable replacement for the original Aras batch loader inside Innovator that allows to import all kind of Items that comes from xls, xlsx and txt . It contains custom UI to specify the type of import and a lot of other helpful feature like CUI elements, an AML editor with syntax check for admins and a preview pane.
Write me a message when you´re interested in an collaboration!
