In addition to installing Linux distributions using the Windows Store and the online list, file systems can be directly imported into WSL.
Check the Alpine Downloads
Look for the mini root filesystem for aarch64 and download it.
In the commands below substitute <username> with your Windows username.
At a Windows Command Prompt import the downloaded filesystem into WSL as a Linux distribution:
wsl --import alpine1 c:\Users\<username>\alpine alpine-minirootfs-3.16.2-aarch64.tar.gz
The name of the distribution will be alpine1.
The storage will be in c:\Users\<username>\alpine
When the import is complete, list the installed distributions:
wsl --list
The new alpine1 distribution will be on the list.
Start alpine:
wsl -d alpine1
Alpine Linux is now running in WSL.