Only QCA ath11k devices have had some Linux work being done. They are currently in the early/testing/alpha driver stage. They also have not been reviewed yet nor merged into upstream Linux. Furthermore, these early drivers only support devices that have an ipq8074 or qca6390.
Until these drivers have been made finalized/made official, reviewed, and merged into Linux/mac80211 - there won't be support in OpenWrt.
Your best bet would be to buy an ipq8074 based AP/router and hope for the best that what you've received wasn't based on a draft ax chip. You'd then have to wait until the ath11k driver has been upstreamed. Between the driver being upstreamed and then having a contributor hack a dts and add support the device into OpenWrt, you're looking at a time frame of 1-3 months. Overall, probably sometime at Q3/Q4 2020 for OpenWrt to gain traction with 802.11ax APs/routers. At worst, Q1 2021 if ath11k takes until Q2 2020 to be upstreamed.