They can because they essentially support Google chipsets, which are not blobby like MediaTek or Qualcomm because Google for all its faults is still relatively open (except their recent change in release schedules is why the Pixel 10 series still only has experimental GrapheneOS support).
Yes, even Apple with its practically infinite resources took 14 years from when it acquired Infineon's mobile chipset unit to launching its C1 modem. So much of the telcos' allegedly open protocols are actually implementation-dependent that it takes a lot of testing on actual mobile networks to validate interop.
No, but they used to publish the source code for the drivers as part of AOSP. Now they no longer publish the device trees. Check out GrapheneOS' other Mastodon posts for the gory details.
Is that actually true? It's such a big deal, and I see little to no work being done on this front.
Anyone have any idea what GrapheneOS actually deblobbed?