About that last point, $sub->&* would rather be equivalent to &$sub, meaning it passes the current value @_ to the subroutine (the comma after &$sub, is not a typo, it's to mark the fact that you can't pass parameters with the ->&* form):

perl -MData::Dump=pp -dEbug

Loading DB routines from perl5db.pl version 1.51
Editor support available.

Enter h or 'h h' for help, or 'perldoc perldebug' for more help.

main::(-e:1):   bug

  DB<1> $a = sub { say pp @_; say 'wantarray' if wantarray }

  DB<2> @_ = qw< Hello World >

  DB<3> $a->()
()
wantarray

  DB<4> $b = $a->();
()

  DB<5> $b = &$a,;
("Hello", "World")

  DB<6> $b = $a->&*;
("Hello", "World")
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