Set Django JSONField value to a JSON null singleton with the Django ORM

Question

Using a Django JSONField on PostgreSQL, say I have the following model

class Foo(models.Model):
    bar = models.JSONField(null=False)

and I want to set a row to have bar=null where null is a single JSON null value (different to a database NULL value).

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I can achieve it through a raw SQL query:

UPDATE "myapp_foo"
SET "bar" = 'null'::jsonb
WHERE "myapp_foo"."id" = <relevant_id>

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The closest things I can do in the ORM is

Foo.objects.filter(id=<relevant_id>).update(bar=None)

but Django is interpreting this as a database NULL and I get the following error:

null value in column "bar" violates not-null constraint

or

Foo.objects.filter(id=<relevant_id>).update(bar="null")

but Django (correctly) interprets this as the JSON string "null"

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Am I missing something or is this a gap in the ORM functionality?