Rusty on Linux, moving from test automation into DevOps. Is a Linux cert (LFCS/RHCSA/Linux+) worth it, or should I just get the hours in?

I've been in the industry about 14 years, mostly test automation, and I'm moving toward DevOps/platform engineering. Day to day I work with GitLab CI/CD, Terraform, Helm/Kubernetes deployments, and some AWS. I'm currently leading a migration of a large number of services onto Kubernetes.

The problem is that I work at a .NET/Windows shop, so I've barely touched Linux in years. I took a basic self-check recently (systemctl/journalctl, finding what's on a port, disk usage, apt, file ownership) and did badly. I knew roughly which tool to reach for but not the actual commands.

My employer pays for certs. My current plan is KCNA, then CKA, Terraform Associate, and AWS Solutions Architect Associate. I wasn't planning on a Linux cert, just a refresher course plus using WSL daily and running a homelab.

Questions:

1. Is LFCS, RHCSA, or Linux+ worth adding for someone aiming at cloud/platform roles, or does CKA cover the "can use Linux" signal well enough?
2. If one is worth it, which, and would you do it before or after CKA?
3. For those who came from a Windows-heavy background, what got your Linux skills to stick when your job didn't require it?
4. How much Linux do you really use in a platform role, compared with what the certs test?

Not looking for reassurance, honest takes welcome.

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