Without support from the vendor they don’t. Mobile computing is so locked down right now that it might be possible that not even the vendor can repair a bricked phone tbh.
Compare it to a broken BIOS on a PC. You can basically throw out your motherboard if you fail while updating it. Some devices have hardware pins used only for provisioning and debugging (JTAG) but they would have to be reverse engineered first.
I actually plan on putting hardware related stuff on an extra pi since I only run a single proxmox node right now. Would be home assistant and nut tools for the ups but I might put pihole and unbound on that as well.
I am worried about the performance though because of home assistant. And it is pretty comfortable to have everything on one host that is far from being used to capacity anyway.