When self-hosting it - it's up for the company that is using the tool hosted on-premises to ensure that all their specific requirements are met - i think DocuSeal provides enough features to make this happen.

AWS S3 to store documents can be integrated with DocuSeal to ensure the documents integrity - AWS services have their own logs that can't be altered and so can be used as a source of trust.

And to ensure that the document was signed by a real person companies can include photo attachments into the documents signing process (this could be a photo of an ID card or a selfie)

Then it is the most toxic thing you can ever self-host. I will gladly pay any company to get all the liability on my behalf.

This is the "I have a friend that does it cheaper" of e-signature solutions.