I have many nerdy friends who have been Linux users for ages. But most of them don't know such a thing as Openwrt exists or have never bothered to give it a try.
It's a very fun piece of software to play with and can be extremely useful for routing traffic.
Wondering why it isn't more popular/widely used.
OpenWrt was relatively popular back in the day when Linksys routers could run Linux. At some point iirc Linksys sadly replaced the default Linux based firmware by a closed source OS, and also decreased the amount of memory for the firmware. A few years ago I saw that there was an option to install OpenWrt in an lxc container, I briefly played with it, nice nostalgia.
There was also some interesting thing from Cisco with their stupid Meraki cloud-managed devices.
I don't know if they still do it, but they used to give out free Meraki APs as "free trial". After that, the license would be deactivated and you'd be left with a paperweight, which meant you'd likely pay to keep using it.
Well, they could run OpenWRT. Free hardware!
Nowadays you can easily run it on a single board computer like the raspberry pi or any x86 mini pcs. You just need to hook up an access point for Wi-Fi which doesn't need to be able to run openwrt.