OK, I somehow thought that you were making a copy of the Coinbase private key associated with your Coinbase account. Yes, “Bitaddress.org” is a “paper wallet” or stainless steel, etc. wallet, but is no better (or worse) than a new address generated by your Mycelium wallet. It is just cold/colder. It all depends if you plan to transact at all (send BTC to family/friends, etc.)...an offline “paper” wallet makes that harder for BTC “noobs”...there are ways around that with barcodes, etc.. If “cold convenience” is needed (Cold storage & able to do transactions) then a “Coldcard” is a great option.
Your method (personal offline “paper” or stainless steel word phrase wallet):
https://youtu.be/VTsHeiBhPIM?si=WTU5cvzIGB7Ks3dX
Coldcard method:
https://youtu.be/FAYmE5-40PQ?si=cTau93Z-zDbZW1Su
I guess it is just a matter of “different strokes for different folks”...thanks for emphasizing the “paper wallet” cold storage method. I am more of an “air-gapped” HW wallet person (Coldcard).
I guess the Bitaddress.org/paper/metal option could be considered the safest cold storage method...no “electronic” access to your private key.
Those were the good old days.