One last note: Why am I being so strict on these rules? You may not remember your first experience with OpenWrt, but I was terrified that I would brick the router, or that it wouldn't work, or that I wouldn't be able to configure it. I only had one router (back in the day when routers were expensive), and it was serving my whole family...
So... I'm looking for a cheap device (well under $US100) that a technically inclined person could, as a lark, install OpenWrt to see if it's as good as we say... If it works, they'll leave it in place. If not, they can back out and put the router back on eBay
Update:
I received a lot of comments (some relevant), but since they didn't contain a recommendation for a router that met all the criteria, I removed them. But let me respond to some of those comments here:
This question is moot - just encourage people to ask in the Forum...
I am asking in the forum. And the responses that came in only provided a couple recommendations that meet the criteria, with lots that didn't meet the requirements. I've been working on OpenWrt/LEDE/CeroWrt for over a decade. It took me several hours to verify the various claims: how could a newcomer make sense of the information?
It is essential to include easy recovery from a failed firmware install.
I intentionally did not include that as a criterion. If we can't be 100% certain that newcomers can install a stable (official) version of the firmware on a supported router - first time, every time - then this is a clear sign that the firmware / router combination is not suitable for newcomers.
There are lots of Wi-Fi standards for different countries...
Yes. Please recommend any router that you can personally assure works fine and meets the criteria.
But what about expandability, or the future?
The target audience for these recommendations is a person who just uses their ISP's modem, and wonders why their network stinks out loud. They never imagined that their router even has software, or firmware, or anything that could be changed. (It just seems to be magic, and poorly-functioning magic at that.)
We are introducing a new concept: that a "normal person" can take control of their network to make things better, more secure, etc. And it doesn't require them to purchase a shiny (more expensive) new router or higher speed internet. In our heart of hearts, we know that OpenWrt will work great.
But... newcomers only want to spend a little time and a few bucks to make the initial experiment. The solution we suggest has to be relatively cheap, and work absolutely correctly the first time.
Furthermore, these people are likely to be running whatever crappy insecure firmware the router came with when they bought it years ago. At least if they're running 23.05.x, we know it's quite secure out of the box.
For the same reason, they mostly don't know about Wifi5, Wifi6, Wifi7, etc. They won't notice if the initial OpenWrt install doesn't have those buzzwords. I have softened requirement, since most of the recommended routers support at least Wifi6.
Once they see that it works, they''ll be "sucked into the OpenWrt ecosystem" and any questions they ask will be way more easily answered.
Finally, PM me with questions on these criteria, or why I included a device or not. But please don't post about any new devices that don't meet all the criteria. Thanks again for the attention to this important question.