You won't have to be a tester to try Windows 10's new, built-in Linux kernel in the near future. Microsoft has confirmed that Windows Subsystem for Linux 2 will be widely available when Windows 10 version 2004 arrives. You'll have to install it manually for a "few months" until an update adds automatic installs and updates, but that's a small price to pay if you want Linux and Windows to coexist in peace and harmony. It'll be easier to set up, at least -- the kernel will now be delivered through Windows Update instead of forcing you to install an entire Windows image.
WSL2's focus isn't so much on basic functionality (there's been an emulator for a while) as it is performance. It should load and run faster, with reduced memory consumption to free up your RAM for other tasks. This prioritization isn't completely surprising. Now that Microsoft is less dependent on Windows sales and more on services like Azure, it benefits when it treats Linux like a first-class citizen. Still, it's clear Microsoft has come a long, long way from the days when it was waging war on Linux and otherwise trying to hold on to its monopoly in computing.