I think the bind qw/Tk::Entry <Key-?>/,sub{Tk->break}); is the laziest solution.

In the case of several TopLevel windows, bindings can be aggregated into a lookup table. Then foreach window any binding is bound to the window and removed for the Tk::Entry class.

It is also useful to bind <Return> to give back the focus for all Tk::Entry widgets.

#!/usr/bin/perl
use warnings;
use strict;

use Tk;

my $mw = MainWindow->new();
   $mw->geometry("200x100+0+0");

$mw->Entry( -text => '',-width => 20)->pack();
$mw->Checkbutton( -text => 'focus on me and press ? or !' )->pack;

my $mwbis = $mw->Toplevel();
   $mwbis->geometry("200x100+300+0");
    
$mwbis->Entry( -text => '',-width => 20)->pack();
$mwbis->Checkbutton( -text => 'focus on me and press ? or !' )->pack;

# a lookup table for all global bindings
my %bind_table = (
   '<KeyRelease-?>' => sub{print "A question mark was pressed!!\n"},
   '<KeyRelease-!>' => sub{print "A esclamation mark was pressed!!\n"}
+,
);


foreach my $window ($mw, $mwbis){
  # assign bindings to all TopLevel
  foreach my $bind (keys %bind_table){
      $window->bind($bind => $bind_table{$bind});
      # remove bindings for all Tk::Entry in all windows
      $window->bind('Tk::Entry', $bind,sub{Tk->break});
  }
  # bind Return to for Tk::Entry to give the focus to parent
  $window->bind('Tk::Entry','<Return>' => sub{$_[0]->parent->focus})
}

MainLoop;
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L*