We have achieved your requirement in sample level. Please refer the custom.js file in the below web all file. Please find the below code snippet;
<script src="https://cdn.syncfusion.com/22.214.171.124/js/web/ej.web.all.min.js"> </script>
We will consider this feature request “Provide an option for File Name when Save the Excel File” in any of our upcoming release.
Could you please check the above sample and get back to us if you need further assistance on this?