Some of the accessories on the site indicate they are for the M10 yet look like they should work for the M5. I know the Accessory Mount works. I have 2 of them and it attaches to the M5 just fine. The charger for the M10 looks identical to the M5 but I am not sure if it is. The replacement leads for the battery charger also look to be compatible. At the very least know that the Accessory mount is compatible and works just fine.
I can't think of any accessories that aren't cross compatible between the M5 and M10 except the camera adjustable mounting plates. The M5 uses a larger bottom plate and a top plate specific for the hot shoe mounting of DSLRs. Ninja plate, TITH, Rod Mount are all interchangeable.
Also the Toad in the Hole is compatible!! Like Brad said I doubt that FF will make different accessories other than the Camera Plate or very specific one for the M5 and in that matter the M15 !!