Neowin published a story that Microsoft has backported WSL2 to Windows 10 versions 1903 and 1909.

Microsoft backports WSL2 to Windows 10 versions 1903 and 1909, updates rolling out now

Microsoft announced that it is backporting WSL2 to Windows 10 versions 1903 and 1909. Cumulative updates are rolling out now to bump 1903 and 1909 builds to 18362.1049 and 18363.1049, respectively.

Microsoft backports WSL2 to Windows 10 versions 1903 and 1909, updates rolling out now