I will list the methods you can download npm tarballs.
curl -s https://registry.npmjs.org/del | jq -r .versions[].dist.tarball | wget -i -
fetch "https://registry.npmjs.org/del" | get versions | pivot | each { get Column1.dist.tarball } | str collect $(char newline) | wget -i -
curl -s https://registry.npmjs.org/del | grep -Po '"tarball":"https.*?\.tgz"' | cut -d '"' -f 4 | wget -i -
$(Invoke-WebRequest "https://registry.npmjs.org/del" | ConvertFrom-Json).versions.PSObject.Properties.Value.dist.tarball | foreach { Invoke-WebRequest -Uri $_ -OutFile $(Split-Path -Path $_ -Leaf) }