limper Honestly it's not clear what you're trying to achieve. It isn't really possible to be 100% anonymous, in the sense of concealing all information about you from everybody. If you use a VPN, that conceals which web sites you visit from your ISP, but your VPN service knows which web sites you visit. If you install a tracking-focused social media app and use it to access things that interest you, the app may well figure out who you are based on your interests alone.
The cited piece provides specific detailed directions but doesn't start off with a threat model, and your question also doesn't state a threat model (i.e., which information you want to conceal from whom, and which resources it is plausible will be brought to bear against you). Without a threat model it's hard to say whether any given individual piece of information leakage is problematic or not, or how applicable any given list of must-do/must-not-do directives is.
To be clear, I OEM-unlocked my device on my home network because I was not trying to conceal from Google the association between the device serial number/IMEI and me. Apparently for the author of that web page such an association would be "UNACCEPTABLE", though no reason is clearly stated. There isn't a single recipe that must be followed, because people have different goals.