You are missing a big part of the needed work. I would suggest this approach. Make a list of every person you have worked with over these 11 years, everyone with whom you had non-trivial/extended interactions. Probably a long list! Go through that list, and think about- which of these people did you like to work with. Which liked working with you. Which ones appreciated the unique things you brought to the table when working on a problem. Be very selective. This is probably a much shorter list! For each of them, track down their email and compose a personal message communicating that you remember working with them on X, you enjoyed the experience. You are looking for a new challenge and would love to get coffee/zoom coffee/touch base. Send the message. After doing this for each of the very selective group, reduce the selectivity a bit and repeat, composing a still personal message, just reaching out.

In terms of skills, yes, you may be helped by figuring out a focus and gaining depth in a particular area. But which area? Here you do need to do another layer of analysis beyond job postings, but you will also need to figure out what interests you, what you would be motivated to do. Which might be more technology or it might at your level of seniority be other areas like business domain or people areas. If business domain or people areas are interesting then you will want to double down on setting up conversations with your network. But if technology is interesting the very best thing to do is the learn in public. Take your lack of knowledge as a strength, start from zero, and use your existing skills to learn how something is implemented, and teach yourself, documenting as you go, to the level of depth that satisfies you. Publish that work. If you have worked at the kernel/file system level you find especially in user space platforms like k8s many oddities and curiosities. Listen to your curiosity and document those oddities. You might actually find something that needs fixing, in that case, submit a PR.

Both of these approaches- reaching out to your network, and following and documenting your curiosity- take time. Doing the job hunt with recruiters does as well. But this way you are growing yourself as an asset, in relationships, and in skills.

HTH. Good luck.