Bonjour: If all the PCB are low voltage then safety compliance is minimal.
Compliance is Depending on the country they will be sold, type of shielding, filters, and EMI sources,
You have both conducted and radiated.
You must weight the cost of compliance and testing with the total engineering and setup eg will you build 100 pcs or 100K pcs?
I would say the majority of such small boards are NOT built to comply even if the (Chinese) mfg put the CE mark.
Survey the market for similar devices and see what the other competitors are doing.
Rather than rely on second/third hand info like the website link, I would do research especially from the compliance standards applicable to the product.
Bon Chance
Jon