My Mikrotik RB750ghr3 suddenly died. I was able to get the TP Link delivered for $49 the next morning from the usual fast-delivery folks. I followed the instructions below, using a linux laptop as the install device. Although somewhat arcane, every step worked perfectly. The only thing that wasn’t obvious is that the first OpenWrt should be the version 23 as recommended; the latest (version 25.12) would not flash. However, once 23 was on-board, a sysupgrade to 25.12 went well. After following the instruction to turn on hardware acceleration, I am getting the full 300 mbps up and down that I pay for. Wireguard and everything else running fine. Its a solid looking and feeling device as well.
A huge thanks to chill1Penguin for such great instructions!
I am posting this as it was somewhat puzzling which no-wifi routers are inexpensive and worthwhile, and easy enough to install OpenWRT onto.