No looping required, thanks to the magic split //:

my (@f) = split // => $s;
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I'd suggest having it in an array instead of individual scalars (it usually ends up being far easier to deal with in the rest of the code), but if you really want it that way:

my (
    $f0,
    $f1,
    $f2,
    $f3,
    $f4,
    $f5,
    $f6,
    $f7,
    $f8,
    $f9,
) = split // => $s;
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