Juraj:
to Klaus_K: the Ublox NINA module has the paperwork done. so even Arduino doesn't have to certificate Arduino 33 BLE.
Unless you sell a Bluetooth product unmodified (e.g. you are a distributor or store) you must list the product at the Bluetooth SIG site and pay the fees.
Have a look at the following link. As you can see Arduino is listing their boards and reference the u-blox NINA module.
https://launchstudio.bluetooth.com/ListingDetails/94711
The Bluetooth SIG ensures everyone who profits from using the Bluetooth technology pays a share for all the costs (patents, running the organization, protection the IP and marketing e.g. trademark, logos ....). You do not acquire the right to sell Bluetooth enabled products by buying a chip or module from anyone. You can find every Bluetooth product on the site from chip, to libraries, modules and industrial or consumer end products.
The same is true for certification. You can use the certification documentation of components as part of your own paperwork but at the end you are the manufacturer of your product and you have to show that it complies with the rules of the country you are selling in.
We can all have a lot of fun playing with these boards, sharing and learning but as soon as you start selling you are jumping into the water with the big fish and they like to protect their investments. You must play by the rules. It seems unfair when you just want to sell a few units but that is the cost of business.