Regulus
Regulus keeps a Windows machine running off to the side and streams each app straight to your desktop over RDP RemoteApp. Word, Explorer, or that one internal tool you're stuck with all open as normal windows, sitting next to your Linux apps.
You won't get a second monitor, or a Windows desktop crammed into a window. You just get the apps, along with a shared clipboard and working sound.
Every app gets its own RemoteApp connection, so it shows up as a real window with its own icon and title. There's no wrapping desktop behind it.
QEMU, FreeRDP, and the agent all live inside the Flatpak sandbox. Close Regulus and Windows shuts down with it, so nothing keeps running in the background.
Windows are drawn straight to Wayland by sdl-freerdp. No XWayland, no flicker, and nothing relaunches itself.
Regulus installs Windows 11 or Windows 10 IoT Enterprise LTSC. It's a small, stable build that Microsoft supports for a decade.
Regulus manages its own QEMU/KVM virtual machine and drives it over QMP. There's no Docker and no dockur image underneath. It boots an unattended IoT LTSC install, then opens a separate FreeRDP /app: connection for each application, the same approach WinBoat and WinApps take. A small agent inside Windows, called Leo, looks after app discovery, icons, and winget installs.
Regulus needs hardware virtualization. Your CPU has to expose Intel VT-x or AMD-V, and Linux has to be able to give Regulus access to the KVM device. That's all. QEMU, FreeRDP, and the rest come bundled.
Regulus ships as a Flatpak. While it's still pre-release, you build and install it from source:
git clone https://github.com/maybejaishkhan/regulus
cd regulus
flatpak-builder --force-clean --user --install --ccache build-dir packages/flatpak/dev.jaish.Regulus.yml
flatpak run dev.jaish.RegulusThen pick Windows 11 or Windows 10 IoT Enterprise LTSC, choose a preset, and let Regulus download the image and set up Windows for you.