Hi JohnHoo3,
Thank you for reaching out Microsoft Community.
Well, upon reviewing if customers can just use the Surface pen to sign a document, yes they can but that's through a PDF application. You may check out this threadfor details.
If this answers your question, please let our Community know by marking this post as an answer. Otherwise, don't hesitate to respond to this thread if you need further assistance.
Kind Regards,
Crest_Z