The newest 10.2.4-1.0-00024 firmware at Codeaurora (https://source.codeaurora.org/quic/qsdk/oss/firmware/ath10k-firmware/plain/ath10k/QCA988X/hw2.0/) seems to have mesh support. I have it running now on my Archer C7v2 (I am not using mesh though), and it works very well. Signal seems stronger too, and I don't have to use "disassoc_low_ack = 0" anymore to prevent the "disconnected due to excessive missing acks" anymore.
[ 16.536646] ath10k_pci 0000:01:00.0: firmware ver 10.2.4-1.0-00024 api 5 features no-p2p,raw-mode,mfp,allows-mesh-bcast crc32 2a48e27d
If anyone wants to test, now you can