The problem is that there has zero interest from QCA to retrofit ath9k with QCN5502 support. Affected users tried to hack their way around to get it at least partially working, but they sadly lack the technical documentation and time/ familiarity with the code base to do this 'properly', so performance is suffering.
If you haven't ordered yet, I would suggest to look for easier to support hardware instead (e.g. ipq40xx, ipq806x, mt7621a+mt7615/mt7915 or mt7622+mt7915).
I have ordered, but it is not a problem to return, if I find a better device, and I fear I don't.
snapshot only, expensive
expensive, big size, but a possibility, I don't see an advantage in comparison to my Archer C7, it cannot be plugged in the outlet
TP-Link RE650 v1
Available, but probably v2 and v2 has less memory
AVM FRITZ!Repeater 1200
Probably available, but there are different version, mostly there is AX at the end. I am not happy with my Fritzbox Wifi, very low signal with a 7390 and cheaper Fritzboxes, I have the box from the ISP and I connected a Nighthawk R7800 with openwrt, so I have a Wifi signal which is a lot better
AVM FRITZ!Repeater 3000
very expensive and the same as with 1200
So it looks like it is not so easy to find a range extender. For the EX7300 I pay about $/€ 50. The mentioned working possibilities are more than 80 bucks.
If you have an idea for a range extender (not a router, plugable into the outlet), please let me know.