WinApps doesn't use a Docker backend btw, you can use any Windows machine running anywhere - cloud, physical, container etc. All you need is the IP address of the box once it's set up.

This looks great though. +1 choosing Qt instead of Electron. -1 for Python though. Otherwise, your approach ticks most of my boxes.

One feature I'd like to see though is reverse file associations - basically associate Linux filetypes inside the Windows VM so that any file you open in a Windows app would open the file in Linux, assuming Linux has a file association for it. Say I've installed Directory Opus in the VM and I want to use it as my primary file manager in Linux, and say I double-click on a .xml file, I would like to open it in the Linux app associated with that filetype (which would be Kate in my case).