IIRC the HP 1920 OEM firmware also has cable testing.
As it happens there is cable test support in OpenWrt via the infrastructure in the Linux kernel (v5.8 or so and later) for cable testing, and on the user-space side in ethtool (ethtool-full package). It's only implemented for Marvell PHYs at the moment, but it should be possible to add support for Realtek PHYs too. I'm currently working on a fix for the Marvell PHY driver on my hardware (Huawei AP5030DN access point). If anyone has any other Marvell PHY devices please chime in on: Ethernet cable test feature bug fix - testers needed which includes more details on the feature - and/or the associated github issue (which includes a debug patch which fixes TDR on the AP5030DN).