npm command not found in wsl
node.exe is NodeJS from your Windows environment - that's for Windows, not WSL.
You need to install NodeJS from the NodeJS repositories inside of WSL in order to use npm and Node within WSL. DO NOT rely on the Windows solutions for installing WSL.
Microsoft has specific documentation on how to do this, provided you're using WSL2. I would suggest following the Microsoft documentation. (Not copied here because it's a fairly involved process 'cause of making sure you've got WSL2 and such)