For anyone who is interested, my Linksys EA6350 v3 (IPQ4018) finally arrived from Amazon UK (Still £34 price matching ebuyer.com) after a long 3 week wait.
Installed OpenWrt 19.07 snapshot, and OpenVPN client.
Speedtests report 29-30 Mbps download speed via ethernet LAN port, and about 26-27 Mbps via 5GHz wifi.
Compared to 14 Mbps from an old Western Digital N750 (AR9344), 13 Mbps from TPlink Archer C50v4 (MT7628), and 10 Mbps from HH5a (Lantiq).