Devices using Zigbee or Zwave will require a hub.
Devices using Bluetooth will require some kind of base station, but in some cases that can be a phone or tablet if it’s always in the same room when you want to use the device. And sometimes you can find a Wi-Fi smart plug that has a Bluetooth remote where the remote only talks to the plug, it doesn’t need its own base station.
Devices using Wi-Fi will just require a Wi-Fi connection.
There aren’t many battery operated Wi-Fi devices because they use up the battery too fast, but there are some buttons that can be used with a SmartThings account without needing a smartthings hub. But they won’t be using zigbee or Z wave.
Also, if you have an Ifttt account, there are more choices, but that service now requires a monthly subscription if you have more than three rules set up so I don’t know if you’re interested in those options.
Or if you have an echo device that has a zigbee hub inside, or a $99 Apple HomePod mini, either of those expand the set of choices for devices.
Anyway, I don’t want to go into a long list of devices that might not work for you, so first can you answer the following questions:
One) what country are you in? The device selection does vary
Two) Will your devices have Wi-Fi access? I know that’s not available for private use in some offices unless you use a hotspot on your phone. The Wi-Fi would have to be on the 2.4 Ghz band. Also, the Wi-Fi cannot require any extra security step, just a basic password.
Three) are you willing to use Ifttt?
Four) do you have an echo plus or Apple HomePod mini in the room or nearby?
Five) do you really need integration with smartthings for this? Or would you be OK just with some smart plugs that you could control with a handheld remote and a phone app?
Six) are you OK with a device that has a plug-in base station if it’s easy to set up and use? this is true of many buttons, especially if you want to use them when you don’t have your phone with you.
OK, let us know the answers to that and I can give you a list of Candidate devices. I think you should definitely be able to find something, but it depends on the details.