Migrating from VBA Excel 2003
You can design userforms to act as the UI then use application.hide to hide the Excel interface, so the user never sees Excel. I've done it on a few projects in the past with no problems.
Since you mention licensing as a reason. LibreOffice might work for you. Probably nothing will just work without some conversion on your part. Depending upon what is being done, you can do a surprising amount in a simple web application, with any number of languages available for free.