Django CheckboxSelectMultiple not displaying in ModelForm

I'm trying to use CheckboxSelectMultiple in a form, instead of the SelectMultiple default. I tried two different ways to make it display as checkboxes, but they both display the default SelectMultiple on my local webpage. Everything else renders correctly ( {{ form.as_table }} ). Would someone point me in the right direction? Thanks,

Django version 3.0.2

Python 3.6.9

models.py

class MyModel(models.Model):
    m2m = models.ManyToManyField('OtherModel', blank=True)

    [...]

forms.py

from django.forms import ModelForm
from myapp.models import MyModel

class MyModelModelForm(ModelForm):
    [...]
    # I tried this...
    m2m = forms.MultipleChoiceField(widget=forms.CheckboxSelectMultiple)

    class Meta:
        model = MyModel
        fields = '__all__'
    
        # or this...
        widgets = {
            'm2m': forms.CheckboxSelectMultiple,
        }

views.py

from django.views.generic.edit import CreateView
from myapp.models import MyModel

class MyModelCreate(CreateView):
    model = MyModel
    fields = '__all__'
    template_name = 'MyApp/mymodel_form.html'

You did not use the form you constructed. You simply constructed a ModelForm, and then let the CreateView create another ModelForm since you did not specify a form_class ^[Django-doc].

You can thus update the CreateView, and work with:

from django.views.generic.edit import CreateView
from myapp.models import MyModel
from myapp.forms import MyModelModelForm

class MyModelCreate(CreateView):
    model = MyModel
    form_class = MyModelModelForm
    template_name = 'MyApp/mymodel_form.html'