Yeah, it looks like it was able to update the DB with the certificates. I also would expect that the 2023 signed boot manager will update if it hasn't already. The KEK is what you don't get in this case - probably due to the age. The device will continue to run and get updates. What you won't get is the updates to the Secure Boot DBX when there are security issues in things like boot loaders and other firmware modules.

Kudos to you for keeping it running that long and to Dell for manufacturing something that lasts. I sympathize with you. I'm still using my Lenovo Yoga Pro 2 that is about the same age as your Dell. I can sense that I'm getting close to getting a new laptop. 🙂