In order for this to be legally useful to users in the EU/UK, this would need to comply with the eIDAS regulations. I’m not sure what that entails, but it would

In order for this to be legally useful to users in the EU/UK, this would need to comply with the eIDAS regulations. I’m not sure what that entails, but it would be worth looking into. A lot of the value of a signature provider comes from it being a neutral trusted third party. They slap a signature and a time stamp on a document, and you can get them to testify that the document existed in a particular state at a particular time.