Fixed #28107 -- Added DatabaseFeatures.allows_group_by_selected_pks_on_model() to allow enabling optimization for unmanaged models.

django/db/backends/base/features.py

@@ -313,3 +313,8 @@ class BaseDatabaseFeatures:
             count, = cursor.fetchone()
             cursor.execute('DROP TABLE ROLLBACK_TEST')
         return count == 0
+
+    def allows_group_by_selected_pks_on_model(self, model):
+        if not self.allows_group_by_selected_pks:
+            return False
+        return model._meta.managed

django/db/models/sql/compiler.py

@@ -171,7 +171,11 @@ class SQLCompiler:
             # database views on which the optimization might not be allowed.
             pks = {
                 expr for expr in expressions
-                if hasattr(expr, 'target') and expr.target.primary_key and expr.target.model._meta.managed
+                if (
+                    hasattr(expr, 'target') and
+                    expr.target.primary_key and
+                    self.connection.features.allows_group_by_selected_pks_on_model(expr.target.model)
+                )
             }
             aliases = {expr.alias for expr in pks}
             expressions = [