Can the Olimex ESP32-EVB be used in a commercial application?
The site you linked to explains why you can't use the evaluation board in a commercial product:


  This evaluation board/kit/module does not fall within the scope of the European Union directives regarding electromagnetic compatibility, FCC, CE or UL and therefore may not meet the technical requirements of these directives or other related documents. 


You can't use it in a commercial product because it isn't certified to meet safety standards (CE, UL) and it isn't certified to meet electromagnetic compatibility standards (FCC, CE.)

Those standards apply not only to the intentional transmitter on the board, also to unintended interference produced by the boards.



That said, the boards themselves may well be engineered such that they can meet the required standards.

They have not been through the process of proving that they meet the standards.

If you use them in your own product then you will have to take them through the approval process, and you will be responsible for making certain that all future pieces continue to meet the standards - even if Olimex changes the design of the boards you purchase from them.

Safer to make your own version of the boards, and have them built and assembled.  You then take your own product through the approval process.  Any changes (and therefore renewal of the approval) are then under your control.