[Moto Z2 Force Accessories] ChozCunningham:
Lets go full bore completely crazy for a moment, price no object.

The market for theae is not your average user, as they are beyond niche and radically change what a smartphone is. Some of below mods can work together, piggybacking to synergize with each other. Most can be remotely controlled by Alexa or other assitants, as smart home devices.

Technically, these are possible, I think. Or nearly so.

A "pass-through" battery pack. It would snap to the back of the phone, and then other mods could snap onto it. Think like a battery sandwich. Requires a new Smart power connector apart from the MOTO connector. Or could be used like normal power pack. Would be *just* thick enough to also have a very flattened usb-a port, which could just be used either as a port for the phone, or to allow it to charge other phones, in case another device needs charging. Cool trick, can output stacked power as parralel or series, as need by other mods.

Super Hotspot Mod. A hardware 5G WiFi access point/router that runs continuously. When attached it uses your existing data as if a standard on-phone APP (rather than appearing as a seperate AP, so existing data plan (sorry you cant upcharge us for using our own gear, Tmobile, #sorrynotsorry. Also, toss in a hardware barcode scanner, ir blaster, and a credit card swipe/chip reader, and a couple multifunction hardware buttons. Whole office in a mod.

A much better speaker mode and sound hardware package. Less JBL grade more professional grade, with hard I/O to studio gear, stereo omni and uni mics, serious hardware DAC, soundbar-like synthesized 3D audio, 1/4" analog inputs with hardware sound modeling (emulates various models of existing and imaginary amps. A lock-on sub-mod attachment adds more hardware pots, led-lit physical buttons and sliders mounting point for clamping to mic stand, drumset, etc. Can fold out from phone into an easel shape allowing speakers to face towards audience while user has the screen in landscape toward them like an easel , Pro musicians and audophiles would pay far more for this than the MOTO itself, it it can all fold down to just over 1" thick with any Z series and stay under 2500$. Would need some battery inside, as well as running game off mains when its working dull bore, and charge both phone and gear. When detached uses a hardwired non adjustable Bluetooth (like the wii or some Logitech wireless keyboards. Personally, I want the gimmicks from nicer BT speakers too, such as chaining speakers with the ability to choose mono, stereo and 4.0+ channel output when networked, and even a group sharing sharable queue for round roben group use for playback. This thing is a beast.

A laser mod. Ir, multiple colors, the works. Can do it all, motorized beams for light shows, scientific research, optically transmit data, etc. "Secretly" can be hardware modified to work with several ///stacked/// pass-through battery mods (mentioned above) could be stacked between phone and the laser mod to allow industrial cutting lasers and other high power goodness I cant even dream of at this hour. Software would allow visual block programming and remote control. No, probably not legal in most developed nations when fully powered.

[°] FM transmitter. Also barely legal: Stack pass-through mods to increase range ad infinitum. Software defaults to max legal output by default based on gps (you can cheat with mock gps. Also allows preporgrammed distress signals with gps coordinates, useful if you get lost for a few days in the woods, etc. Designed to meet military water and impact resistance specs, and also wrap around to protect the phone. Includes a Swiss army-like toothpick toothpick, tweezers, blade, saw, analog ompass, screwdriver and magnifying lens because why nkt? . :) when detached, has compartment to hold things on side that fafes phone. Last but not least, ads a lens to the camera (s) to increase optical zoom. Finally, includes tiny solar trickle charger to keep it running longer away from civilization. This could all really save lives.

Signal mod. Increases range of phones wireless I/Os, like Bluetooth, WiFi and NFC. Adds strong IR blaster can be dialed up levels similar to contemporary outdoor lasertag equipment.

Camcorder. Will record and livesteaam true 8K video (might need 5G added) is as close to a pro cam as posaible. Made to fold out from phone to let you see screen and point the lens out towards target to record.

Badass projector. Can go bigger than current model (stack some battery mkds to up the lumens, supports a larger famut, has ir sensors to allow it yous as an interactive multitoch 2nd or mirrored screen.

DSLR Mod. Either CHEAPER or Better than current offering. Standard interchangable lens, less zoom, right hand grip bulge is packing a nice battery. Buttons are crispy. Allows use of its own flass, a snap on bigger flash, and or the existing led flash on phone, HAS A &/ (*@ tripod mount!!!! The on "phone cameras are coordinated to add goodies like bokeh, 3D photography... , whatever. Can use WiFi direct to chain into muti angle recording.

Yes, these are pretty far out there in 2018. Yes, no one could afford most of them. Yes, some are potentially dangerous, disruptive, and very illegal to purchase most places that would even sell this phone Yes, I know. I was going with the spirit of the OP, I feel. Other than that.... thoughts? Feelings?