Update from October 2024:
OpenAI has released a version of the desktop app for Windows computers.
Here is the link to the download page for all apps, in case the specific link should change in the future.
https://openai.com/chatgpt/download/
It is currently at the very bottom.
Hi!
The desktop app is currently available only for certain types of Apple computers.
I am also waiting for a Windows release which has been announced for later (November) this year.
Hope this helps somewhat.