I am trying to export CatBoost model object to json directly, without saving to a file.

Following this Tutorial,

import json

...

cls.save_model(
    "model.json",
    format="json",
    categorical features.
)

model = json.load(open("model.json", "r"))

At this stage we got json (not CatBoostClassifier) in model object after these steps.

Is there any way to get exact json by some method call maybe?