CodexAG Technically, it is possible to disable all hardware like microphones and such, the Nitrophone 4/4 Pro, which is a Google Pixel 8/8 Pro has done it, but I doubt its something I'd do myself. They have done it with Pixels 4a, 6 series (a, 6, 6Pro), 7 series and now 8 series. Keep in mind, they have the option of paying 400€ extra to remove microphones and cameras, not put in kill switches, which is a more permanent solution, so kill switches maybe weren't possible?
Removable battery? That is a much taller order! It would require a total redesign, the Pixel battery in the 7Pro and 8Pro isn't in a very convenient position, and the back is a solid piece of glass!
Nitrophone is really just an expensive Pixel with option of having hardware removed, and having GrapheneOS pre-installed. Nothing special.