You should be able to use any button device. There’s nothing really special about the Aeon button in a SmartThings environment.
How big is the area that you want to cover? And, perhaps most importantly, how critical is the reliability? I myself have a panic button as a medical monitoring device, but I just would never use SmartThings for this. Mine has GPS and cellular capability, which means it’s also useful when I’m away from home. It costs $20 a month, but includes fall detection, and I feel confident in its reliability.
If you do want to use something directly with SmartThings and you’re OK with the base reliability of the system, You might want to try one of the zigbee devices, just because I know those will work through repeaters. That’s exactly how the smartthings brand arrival sensor works. There are a number of different button type zigbee devices that work with SmartThings, although they are going to require that the SmartThings cloud be available, another reason why I use an entirely different system.
I know a lot of people now rely on the Amazon echo Dot placed strategically throughout the home, because you can either have it start a SmartThings routine or, if you happen to have AT&T, you can have it send a text from your account. But some people have cognitive challenges that might mean they couldn’t remember exactly what to say in an emergency.
I know I’m being hesitant in recommending specific Devices, it just depends very much on exactly what use case you’re trying to solve. As a person who needs a reliable panic button system (I’m quadriparetic), I’m just quite cautious about trying to use any non-cellular system for this Purpose.