In practice, because Rust libraries are always statically-linked, the MPL-2.0 is equivalent to the LGPL in spirit. Meanwhile, because of the static linking restrictions in the LGPL, the LGPL is effectively no different from the GPL. Hence, you’re going to find a lot of open source copyleft projects from the Rust ecosystem preferring either GPL or MPL-2.0, where MPL-2.0 is used in libraries where LGPL would have used previously in C projects. Dynamic linking is essentially going the way of the Dodo.

The Linux kernel already allows proprietary modules via DKMS, and a handful of vendors have been using this for decades, so this is no different. Case in point: NVIDIA driver, and Android vendor drivers.

All source code in Rust is statically-linked when compiled, which thereby renders the LGPL no different from the GPL in practice. For Rust, the MPL-2.0 is a better license because it does not have the linking restriction.

NVIDIA believes they’ll have the Vulkan on Wayland issue fixed in the 550 driver that they are planning to release early this year. Someone’s working on a fix in wgpu that happens to also boost performance for every driver in demos.

We’ve been using COSMIC on our systems since summer of last year. Some graphics drivers have issues, particularly NVIDIA drivers using Vulkan on Wayland. There are some XWayland bugs from time to time. It is very usable as is, but some settings aren’t implemented yet, and some toolkit features aren’t fully implemented.