This is not Sony, Panasonic or Phillips's fault as they are stuck using Mediatek. TCL ends up using one of its HDMI 2.0 ports as the eARC port but I think that means they have to use their own chipset and I hear mixed reviews about the reliability of that eARC port.
The best work-around is to purchase a 3rd party HDMI 2.1 switch (they cost ~US$30-40 if you look on-line) - some of which have an automatic switch function (although from experience the automatic switching doesn't always work smoothly). Otherwise you can use the remote to switch inputs on that device - but that means yet another remote!
I honestly think the best solution would be for the manufacturers to at least sell their own proprietary HDMI 2.1 switch accessory that works smoothly with their own OS. This would make sense because the TV's OS would recognize them as additional inputs in the UI - meaning you don't need another remote and you can then customize picture settings for each of those inputs. It would mitigate the competitive disadvantage they would have compared to LG or Samsung who typically have 4 HDMI 2.1 ports using their own proprietary chipsets.