Try Turris Omnia, the open source router | Opensource.com
NETGEAR does open source (hardware) router - Make:
Open Source Router Platforms - Part 1: The Hardware
OPNsense® a true open source security platform and more - OPNsense® is a true open source firewall and more
Review: 6 slick open source routers | InfoWorld
Amazon.com: youyeetoo BPI R2 Pro Open Source Smart Router Developement Board by RK3568 0.8TOPS 2G LPDDR4 16G EMMC 5 Gigabit Port OpenWRT Linux for IOT NAS Smart Home Gateway (with Power) :
Amazon.com: Linksys Open Source Dual-Band Gigabit WiFi Wireless Router, Speeds up to (AC1900) 1.9Gbps - WRT1900ACS : Electronics
New Linksys 802.11AC WRT router allows open source customization - Help Net Security