I have an R7800 test unit, whose ath10k driver crashes upon first boot with no WiFi interface option in LuCI.
I found a similar case but for a D7800 and the fix was to replace the following files from someone without the issue:
D7800 thread of the issue:
I used the D7800's files from the ath10k functional.zip from the above thread and I had functional WiFi after that.
If anyone has the same files but for the R7800 without the crash issue, could you please post it, I still get occasional drops on the 5Ghz radio so I'm wondering if having the cal-pci files from another R7800 will fix it.