Same notification on my unsupported retina MBPro 15, mid-2012 running BSur 11.0.1 (20B29).
What I found:
1. There is no app called 'Get to Know Your Mac' so you can't turn off its notification.
2. When in Finder, click on Help Menu and you'll see 'Get to Know Your MacBook Air.'
3. That 'Get to Know Your MacBook Air' entry is missing when on a MBPro 13, 2017, 14,2 running BSur 11.0.1 (20B29).