Hey how's it going?
So, even though I'm not an active Adafruit contributor, I do use a ton of various microcontrollers on a regular basis for doing little side projects. I've been planning on putting together a desktop application at some point in the near future to pull Adafruit IO feed data and display it on the app, to save from having to always open up a browser and pull up IO that way. When I get around to it I can let you know, but in the mean time, I would highly recommend using something a lot more simple and direct to achieve your goals..i.e. NOT using C#.
Granted, I have only worked on a small number of C# programs. I have however had a blast at writing tons of python applications that communicate with Adafruit IO using their helper libraries. I have a GitHub repo that uses regular Python running on a Raspberry Pi to communicate with AIO to publish sensor readings from a Pimoroni Enviro Feather. They included it in the contrib section of their repo. I encourage you to check it out, as well as the Adafruit "Blinka" library, which my program uses. It's an abstraction layer that allows you to use regular Python to interact with sensors, as well as use the Adafruit IO helper libraries to send and retrieve values.
If you are only pulling feed data, you shouldn't even need Blinka, just pip install the adafruit-io package!!!
Check it out!
https://github.com/dedSyn4ps3/EnviroPlus-FeatherWing
https://pypi.org/project/adafruit-io/