Inquiry

When was the last time a new model was added? also is this for deviation or for the radio I use which is the Jumper T8SG?

Models are not "added" and not specifically made by the developers of Deviation, though they may share their model configs.
Protocols and OS are made by the developers and helpers with the skills to do so (I'm not in that category, I'm only a user of Deviation)
Model ini's are generally "shared" by "users" of Deviation, you can find shared model ini's in the model config section of which you are already aware of, use the search feature of the forums.
Other than switch assignment, model configs are generally transferable to or from all Deviated Tx's.

As the T8SG is a recently new Tx don't expect to find many model configs specifically for it in the configs section, you will need to find configs from other users and adapt it for T8SG.