@trevdev I too like #OpenWRT . I suggest that you don't start from the hardware, and work towards OpenWRT. Rather start from OpenWRT, and work towards the hardware. I suggest keep this firmware selector handy:
https://firmware-selector.openwrt.org/
...and then go shopping for used routers at stores with many models, reading the model off the underside of the router - *including hardware revision*. The *revision* probably won't be on the box, and is very unlikely to be mentioned in any online ad.
Be sure to get a router with at least 16MB of flash. Mediatek wifi chipsets, mentioned in the specs for the router, are the most linux-compatible ones.