Depends where you are but contracts and other legal documents are only ultimately enforceable in court usually. Electronic signatures tend to shorten that process somewhat as they provide signatory verification, contract integrity and ID verification so it's seen as a legal risk and cost mitigation rather than an actual hard contractual requirement.

It depends on jurisdiction you are located in and the level of legal safety and acceptance you need. Our solution is already able to digitally sign the document which kind of makes it tamper proof and electronically sign(draw annotations) which will have you covered in most regions. Some regions have specific laws for example India has IT Act 2000, UETA & ESIGN Act while Europe has eIDAS.

European Union (and some states connecting with the same infrastructure, like Switzerland), have standardized formats as well as defined CAs that provide certificates for "qualified" signatures, which have the same legal weight as if you had a printed document with physical signature.

DocuSign supports those mainly through some interop connections where, for example, a qualified signature vendor provides an API that DocuSign can use to sign the document.

You are right, that is precisely the route we will also have to take for certain regions. For example in India, there are only 3 entities that are authorized by the government to enable Aadhaar based e-signature. We will have to integrate with any of those in order to be compliant. We have already started working in this direction.

Similar approach would be for signing documents in China.

More than aadhar enabled signatures, India has pfx based digital signature system in place which is legally acceptable as good as a physical hand signature.

There is one state agency in USA that requires wet black ink for contracts. I forgot which state it is, this happened two years ago. They said no expectations, it have to be wet black signature, period. They will inspect the PDF to check the signature that it is not e-signed.

It was odd because I handled federal and state contracts in previous job, they don't have a problem with e-signature.