Well it depends on the profile you're in the sales process:-
If you're the frontend guy who is liable for all the Sales then it won't be of great use as handling operations(sales) and handling purchasers is altogether completely different tasks.
Skillset needed for handling operations and Sales is sort of completely different.
The salesperson is quick-witted and think on their feet and are responsible for the company's sales
The operations guy on the opposite hand is aware of the full flow of the product and all things associated with the sales of a selected product.
So it all depends on the profile in which you have worked.
If you were in operations as SAP end-user then Yes it will definitely help you build a career as SAP SD consultant by doing SAP SD certification.
If you fall in the other scenario then also you can switch career if you are interested to go in a technical job and ready to move to the backend of the Operations.
All the best!!
Also, you can go through the SAP SD interview questions for your career growth.