Sure, close can wait for "-|". But why not waitpid?

$ perl -E'
    $pid = open(my $pipe, "-|", "perl -e'\''sleep 5; exit 3'\''");
    say time;
    waitpid($pid, 0);
    say time;
    say $?>>8;
'
1280685258
1280685263
3
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waitpid is documented with:

Waits for a particular child process to terminate and returns the pid of the deceased process, or -1 if there is no such child process.

The status is returned in $? and ${^CHILD_ERROR_NATIVE}.