You did not mention what hearing aid models you are using with your Samsung Note20 Ultra phone.
Here is a link to the ReSound website where you can find information about phone compatibilty
Compatibility5
ReSound Smart Hearing aids enable you to stream from virtually any audio source and personalize your sound on the go. Find more information here.
Here is an older article (from 2018) about truly hands-free calling without additional accessory.
The Complete Guide to Hearing Aid Types, Cost, Brands, and More1
We help you understand hearing aids. Learn about hearing aid types, styles, features, brands, cost, insurance options, and feel confident when buying one.
Quote from reply of this article
Several brands stream the calls directly to your hearing devices, among them Signia, Oticon, ReSound, & Starkey. So hearing the other party is simple. For them to hear you, however, you either have to hold the phone near your mouth or, put the phone upside down in the shirt pocket or, put the phone in a lanyard phone case and hang this around your neck or, put the phone up in your visor while driving. So that people on the phone can hear you well.
Since i do not own a ReSound One/Omnia hearing aid, i do not know if a ReSound model support fully hands free with android phones.
Maybe other members can chime in, to give you an answer for this question.