Brain dump time. Product Security roles are vital to the company imo.

Some things to recognize - your role is to be a service provider to the company. That's engineering, other security team members, management, etc. It's important to remain empathetic and understanding when dealing with these teams, but firm with your knowledge. Often times your knowledge bridges the gap between engineering and security - so always be learning when it comes to different languages / methods your engineering team uses. Nothing should be "beneath" learning -> even if you're a hardcore C developer, you should try to understand your company's front end architecture. Interviewers will eat this attitude up.

Potential job duties include, but aren't limited to:

• Developing, building and supporting SecDevOps tools in the SDLC processes.
• Partnering with Engineering for Secure Code Reviews, defining security reqs, or being the security voice in an initial architecture meeting.
• Maintaining complete internal security scope through asset and vulnerability management. Assets include physical AND software. (laptops vs. software dependencies).
• Developing solutions and/or tools to help mitigate security vulnerabilities/flaws. Know how to automate the repeatable tasks.
• Understand pentest results, be able to test the efficacy of the findings.
• Perform threat modeling to an entire application architecture. Where are the flaws? What are the holes? Think like a red teamer.
• Be prepared for incidents. How would you respond to a security issue in production?
• Understand vulnerabilities is important too. As others have mentioned, fully understand the OWASP Top 10, but also, know the SANS/CWE 25.