So far we have done all our ath11k testing under special kernels (usually to pull in patches yet to be accepted) so that is why ath11k hasn’t been in our kernel config.
Now that OpenWrt is adopting 5.15 I intend to look at it again soon.
The earlier QCN9074 firmwares required a few special settings to work, namely:
CONFIG_CMA_SIZE_MBYTES=128
As far as I can tell, the Debian kernels set the CMA to 64MiB which may not be large enough. Our default (non-ath11k) config has 16MiB which is too small.
(Though I understand Qualcomm has/was going to release a firmware that removes this requirement. Other ath11k chips like the QCA6390 do not have this problem)
FYI we have since tested various other vendors. It is now my opinion that the MediaTek MT7915 chipset is the best combination of driver stability (the mainline/OpenWrt driver has worked well in our tests) and features (working dual-band dual concurrent). Unfortunately the cards aren’t stocked as widely as the ath11k ones.