The firmware can't be replaced with Coreboot unfortunately, but it is fantastic for a laptop. I have never seen a BIOS with so many configurable settings. There's even a key combo which shuts off all radio, lights and LEDs, which of course can be configured in detail.
Don't get the rubberized keyboard because it's impossible to type a sentence on. I also suggest ordering the m.2 NVMe separately to save serious money, and the Snapdragon X55 DW5930e modem from Aliexpress at a fraction of the price.
I've also heard legends about how great Dell's Worldwide repair program is where people have had parts delivered to them next day on the island of Borneo in Indonesia, but that's yet to be tested.