While kernel-default 5.10rc1 (from Kernel:HEAD) includes the ath11k driver
(fixed via 322b60ceb0f321b4b9c41717f7306c0dbaf0279b), the firmware is still
missing even in kernel-firmware-20201023-338.1.noarch:

[   26.249141] ath11k_pci 0000:55:00.0: WARNING: ath11k PCI support is
experimental!
[   26.249178] ath11k_pci 0000:55:00.0: BAR 0: assigned [mem
0x8e300000-0x8e3fffff 64bit]
[   26.249196] ath11k_pci 0000:55:00.0: enabling device (0000 -> 0002)
[   26.325561] mhi 0000:55:00.0: Requested to power ON
[   26.325648] mhi 0000:55:00.0: Power on setup success
[   26.325693] mhi 0000:55:00.0: Direct firmware load for
ath11k/QCA6390/hw2.0/amss.bin failed with error -2
[   26.325695] mhi 0000:55:00.0: Error loading firmware: -2

https://github.com/kvalo/ath11k-firmware might still be missing?