Form field choices not showing when loop through in Django template

forms.py

SHIPPING_CHOICES = (
    ('S', 'standard'),
    ('E', 'express'),
)


class Shipping(forms.Form):
    shipping_option = forms.ChoiceField(widget=forms.RadioSelect, choices=SHIPPING_CHOICES)
    cost = forms.CharField(required=False)

views.py

class OrderSummaryView(LoginRequiredMixin, View):
    
    def get(self, *args, **kwargs):
        try:
            order = Order.objects.get(user=self.request.user, ordered=False)
            form = Shipping()
            context = {
                'object' : order,
                'couponform': CouponForm(),
                'DISPLAY_COUPON_FORM': True,
            }
            return render(self.request, 'cart.html', context)
        except ObjectDoesNotExist:
            messages.info(self.request, "You do not have an active order")
            return redirect('estores:home')
    
    def post(self, *args, **kwargs):
        # ...

cart.html

{% for value, name in form.shipping_option.choices %}
<div class="card">
    <div class="card-header" id="heading-4">
	    <div class="card-title">
            <input id="{{ name }}" type="radio" name="shipping_option" value="{{ value }}" class="button" required>
            <label for="{{ name }}">{{ name }}</label>
        </div>
	</div>
</div>
{% endfor %}

I don't know why but I have been trying to make it work but it won't work at all. I want to be able to loop through the choices available for shipping options.
So far I was able to do something like that for the payment option and it worked.

1. Pass 'form': form in context.

form = Shipping()
context = {
    'form': form,  # Add this
    'object' : order,
    'couponform': CouponForm(),
    'DISPLAY_COUPON_FORM': True,
}

2. form.shipping_option is a BoundField.
   To access the field's choices, do form.shipping_option.field.choices.

{% for value, name in form.shipping_option.choices       %}  # Change this
{% for value, name in form.shipping_option.field.choices %}  # to this