Anywhere you can use “normal” (classic) Bluetooth audio. That means pretty much any phone, any computer.
One would wish that is true but if the bluetooth source is not compliant with everything the ConnectClip expects, it may not work (reliably). Early on, Oticon (in the US at least) provided a Sennheiser (now EPOS in the US) BTD 800 USB Bluetooth dongle with the ConnectClip in order to get around incompatibilities in the Bluetooth implementation of computers. I had to use one with an iMac Pro and Oticon Technical support suggested that the dongle be used on any desktop computer as many had bluetooth issues that prevented stable and reliable use of the ConnectClip. They said that most laptops had better Bluetooth implementations and it wasn’t needed as often. I have no idea about phones as I’ve used an iPhone that connects directly with my OPN/OPN S/ More aids without using the ConnectClip 
Of interest, EPOS provides that same dongle (or an equivalent USB-C version) with their high end headphones/headsets that use bluetooth. Jabra has a similar device for their high end headphones/headsets.
I did find this in an Oticon White Paper about the ConnectClip from 2019:
- Which computers can be used with the ConnectClip? We recommend using a BTD 800 USB dongle for the most stable connection with the ConnectClip.
I have no idea if that is still the recommendation but I do use it to prevent dropouts when streaming from my iMac to my More 1 aids via my ConnectClip. Note that I also had the firmware of the ConnectClip updated by my provider as another possible fix for the issues I used to have.
I hope that when Bluetooth 5.3 rolls out in phones and computers and hearing aids that things will “just work” but I certainly don’t expect that to be true. I expect that there will be many buggy and/or incomplete implementations of 5.3 and the codec and other stuff so things will be a bit frustrating for a while. Hopefully issues will be fixable by updated firmware. 