Openwrt VPN with Private Internet Access (PIA)

PIA doesn’t provide docs for using their VPN through OpenWrt. They seem to prefer that you use their apps. A post on the OpenWrt forums lays out how to connect to PIA VPN from an OpenWrt device.
forum.openwrt.org/t/private-internet-access-pia-wireguard-vpn-on-openwrt/155475