Apple TV 3 gen

no, appletv 3g does not have storage to host apps, the third party stuff they have are apple server-side channels, it being an old unsupported way of handling it I doubt they will be adding more server-side stuff since they added amazon

Yes, it is really beyond obsolete. I'd recommend a 4K model, you will be much happier and enjoy many more apps to select from than the extremely limited Apple TV 3.