What skills or certifications are most valuable for a Salesforce UX Designer?

Salesforce UX Designers should have these two certifications minimum depending on their level and responsibilities: https://trailhead.salesforce.com/en/credentials/designeroverview/

If they are in production delivery they will need additional Consultant and Developer certifications depending on what they are designing for (ie. Admin, Platform App Builder, Business Analyst, Sales Consultant, Agentforce Specialist)