Not a lawyer, but I know the position in the UK is pretty simple and much the same.

The purpose of someone like Docusign is to provide a trusted third party to provide evidence.

For most purposes GPG signed email (or anything else with a similar signature) would work perfectly well provided you could prove who the keys belong to. In fact it would be better than DOcusign who can (from the few documents I have signed) ultimately only really show they sent an email with a signing link to your email address.

The last one from them has a warning:

"Do Not Share This Email This e-mail contains a secure link to DocuSign. Please do not share this e-mail, link or access code with others."