in reply to How to export hash references
Package Foo;
This isn't valid. In Perl, package is all in lowercase.
Your actual problem (once that's fixed) is that you are not escaping the dollar symbol.
$ perl -I. -MFoo=$env -le 'print scalar keys %$env' 0 $ perl -I. -MFoo=\$env -le 'print scalar keys %$env' 76
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