Can you recover a modern Chromebook that has had all of its Flash memories tampered with or wiped externally, with just a USB cable? With a debug cable? That seems to be one of the major things that sets apart iDevices from others.
At least this design doc still says local attacks involving e.g. replacing writable storage are out of scope (which they very much aren't for iDevices):
https://www.chromium.org/chromium-os/chromiumos-design-docs/...
From block diagrams it seems Cr50 security chip in recent Chromebooks just interfaces with AP Flash and the write protect pin, and thus verified boot isn't tied to silicon tamper resistance. That puts Chromebook at around the same level as T2 Macs in terms of tamper-resistance, in fact a bit worse (on T2s the T2 chip is the flash from the AP's point of view, so you can't just tamper with an external flash memory. You could MITM it in principle, though I heard the T2 Mac boards are also designed to make this difficult to pull off with buried traces).
Digging a bit more (the docs on this are really scattered...), it seems Cr50 RW storage can be recovered from the RO loader by using a physical USB-UART cable, but that requires taking apart the machine, since it won't work over USB, only UART. There is no mention of any Boot ROM recovery mechanism or of how the RO firmware is authenticated; RO is supposed to be "Read Only" in on-chip Flash, but eliminating every avenue for compromise of writable Flash is very hard (e.g. glitching the Boot ROM; I've seen too many "secure" microcontrollers compromised to bypass read or write protect in various ways...), so this approach is quite a bit weaker than Apple's: on these devices, you need specialized hardware to go to the lowest level of recovery, and you can't even recover from certain kinds of volatile storage loss or compromise, while on Apple devices any end user with no specialized knowledge can follow a few simple documented steps with another machine and a USB cable and an app in the App Store (or idevicerestore) to fully, securely, and confidently restore all the writable firmware on the machine to factory condition, and the process relies only on truly immutable mask ROM*.
* I can't say for sure there isn't any auxiliary writable flash that would let you brick the machine in some other way, but I haven't found anything yet. The prime suspect, the USB-PD controller chip that's in the path of the DFU USB connection (and thus could break it if it doesn't work), smells like it boots from ROM until the OS instructs it to launch the application image from Flash. It reports being in "DFU" mode until we issue the first power state switch command to bring it up, and we know these chips are custom Apple versions with Apple ROMs and the ROM does contain most of the USB-PD stack... so this sounds like the kind of thing Apple would get TI to do, since they really care about being resistant to bricks and persistent compromise.