Is it possible to connect a 100-240V charger to a 220 V network?

Hello, such a thing, I bought a hearing aid in the United States with a rechargeable battery. The charger says Input AC100-240V 50 / 60Hz 0.2A Max. Tell me, can I charge in a country where the voltage is 220 V? I called their tech support - they say no, 220 is indicated just in case, if suddenly they give 150 V, for example. But a friend, an electrical engineer, graduated from the university this year, and also took equipment in the USA, he says they are wrong, they also said that to him, but everything worked without a voltage transformer. Tell me, who is right, please!