My problem isn't just high lag and disconnects when gaming or the terrible flent graphs posted elsewhere, it is also annoying things like having to ask the smart speaker multiple times to turn off the smart lights. There are an ever growing number of IoT devices around, many only work on 2.4GHz. This could be just a few metres away in the same room. If I solve this broken 2.4GHz problem I also solve my other problems without needing the Cadillac solution of multiple APs.
It seems like the r7800 has been discontinued. Amazon.com only has five left in stock, and that is from a third party seller that doesn't ship to Canada. I don't know of a similar ath10k device?
So it feel like the answer to my question is "there aren't any great ones". The Archer C7 v5 was working in my home. Therefore the Archer C7 is probably the best WiFi device with OpenWrt support one can buy in 2021. As Warlock said above maybe the DIR-882, etc are also good, provided one is willing to run snapshot builds.
Since I didn't feel like gambling on a device that I need to run snapshot on I've picked up an e8450 to get me by for now. Hopefully there is support soon. In the mean time I'm running stock firmware and have a working household again.
Thank you everybody for the suggestions.