Have you explored using the Status field when setting up a new Vendor or Customer?  You could put the new Customer/Vendor On Hold and then the reviewer/approver could use the Vendor list to look for On Hold vendors to review and remove from hold and make active.

@srigowritk, from what i understand, the business requirement is the need to avoid duplicate vendors (the same vendor already exists and someone previously created it) or avoid creating the new vendor at all because you have a different vendor that you already use and there is a process amongst various internal stakeholders to introduce new vendors - possibly, routing through approvals (as you suggest) to these various parties to sign-off before the vendor is created?

@srigowritk this isn’t currently supported in Acumatica.  However, here is an Idea that you can vote on and add your requirements.