Popular brands of Linux-based laptops have poor support locally. You may be able to buy a unit from say System 76, but if you have any issues you're screwed.

Dell is a decent choice, but make sure that you look up reviews beforehand as many of these laptops have either Bluetooth/WiFi chips that don't play nice with Linux. Onboard/discrete graphics switching (Optimus) may also have issues with the low-power mode not being properly supported.

WRT to your requirement on running DL, I would recommend you scrap the idea of running models on your laptop and push the compute to a server/cloud. The additional performance benefits of being able to run things locally is heavily outweighed by the cost.