Some websites indicate the need to obtain Bluetooth certification.

I am aware of the high cost of registering a product when rebranding, even when incorporating a product that already has Bluetooth certification.

I would expect that if one does not use the Bluetooth patent and logo, one does not need to obtain Bluetooth certification, but I do not know how to avoid using the Bluetooth patent.
Is the Bluetooth patent included in the hardware or in a specific library?

Bluetooth SIG : Bluetooth Qualification Process Overview
https://www.bluetooth.com/develop-with-bluetooth/qualification-listing/

Do I Need to Qualify?
https://support.bluetooth.com/hc/en-us/articles/360049018272-Do-I-Need-to-Qualify-

Bluetooth認証の必要性とSIG認証のための工数・費用の削減する方法とは？
https://www.tjsys.co.jp/embedded/netnucleus-bt/bt-certify-costcut.htm

I was thinking of selling a Bluetooth product using M5Stack.
I then learned that I may need to obtain Bluetooth certification.

What are the conditions for obtaining Bluetooth certification?

I do not plan to use the Bluetooth logo.
Does the use of specific libraries require certification?
Or is certification required if I use hardware with Bluetooth capabilities?