Are you a C# programmer who wants to write an app for the Trezor? Have a look:

https://github.com/MelbourneDeveloper/Trezor.Net

I recently tested and fixed it for Trezor Model T. Please grab it and log any issues etc. on GitHub. The equivalent KeepKey library is based on Trezor.Net and is available here:

https://github.com/MelbourneDeveloper/KeepKey.Net

Also, for good measure:

https://github.com/MelbourneDeveloper/Ledger.Net

If you are a really nice person, you could even write some code and submit a pull request.