I think focus and efforts should be directed at making good software for Linux. And I do not think that porting OSS and free software to closed systems is a good strategy for converting users.
Users switch from macOS and Windows to Linux for all kinds of reasons, but there is no point in trying to "lure" them in any way. It will be of own volition.
That said, I think this is but a small part of the problem. The bigger enemies are the bundling of Windows with new computer (no separate purchase of the OS), and windows-only games. They're the main reasons behind the proprietary hegemony on the desktop.
When so few desktop computer run Linux, half-heartedly supporting Windows and MacOS comes of as a bit haughty. But if Free platforms are the norm, supporting the proprietary ones at all will actually sound generous.
Proprietary OS users are going to judge Inkscape (or Gimp, or any other Free Software) from what they see on their platform. If it lags and doesn't support High DPI on their platform, they're going to assume the same is true of the GNU/Linux version.
Some users won't switch because of this faulty assumption.
Native UI… while there is little point it catering to users who won't switch anyway, it will still reflect badly on the application. Widgets that look like "something out of the 90's" will say to the user "I am an old unmaintained app" whether that's true or not. Users are highly influenced by an application's look.