The business world is shifting greatly towards delivering exceptional Customer Experience (CX) and most Product marketing departments are being aligned with the CX teams to delight customers. Would you advice a product marketer to get certification in CX if they wish to grow in their field?

I've been in PMM roles in quite a few CX oriented SaaS companies. 

I would say, No. 

A CX certification would not help. Having worked in customer-facing roles does help, a lot. That could be in Implementations, Customer Success and/or Sales Engineering. That sort of real world experience is not something a certification could help you with. 

At the same time, just simply read more. The last 5-7 years has seen a universal move to digital channels across Banking, Retail, and other industries. That's creating some new challenges in improving the customer experience. Additionally, companies like Amazon are diluting the brand power of the brands that sell on Amazon. This is all causing CX to be vitally important. Scott Galloway is a good thought leader in the Retail space. There are plenty others that offer the understanding of the market forces at play elevating CX as a differentiator. I'm not sure if any certification provides this understanding.