Tech Certifications

I was previously certified as a Workday Functional HCM Consultant working in a Solution Architect role but lost certification after taking time away from the corporate world. It is hard to get rehired in this space without being already certified. Is anyone aware of how I could get Workday certifications on my own? Or know of any companies that would offer to certify me after hire? On a side note, I would also love to explore Salesforce and Slack certifications. I think being an expert advisor and solution designer for Workday, Salesforce and Slack for companies would be ideal. Many companies use all or some and try (or should try) to integrate them to get the best user experience and ROI on these tools. Advice on how to become certified for Slack and Salesforce (or companies that would provide them to you upon hire) would be appreciated. I have been doing the Trailhead (free) training for Salesforce on my own but not sure how transferable that would be for becoming a hired consultant?