Hovermode/Spikemode for ternary diagram (ternary plot)

Hi everyone,

I would like to ask if there is a spikemode for ternary diagram (ternary plot)?

For me, the ternary diagram is a bit hard to read, and I have to google for a visual annotation aid like the following screenshot (which is so easy to read)

The first thought that comes to my mind is the use of hovermode and spikemode
see example: https://codepen.io/Lexachoc/pen/wvOReVv
But this only works for cartesian plots, and not the ternary plot, see example: https://codepen.io/Lexachoc/pen/yLwGozo

But I can’t find the keyword in Layout.ternary in JavaScript

Screenshot:

Live demo (need some time to initialize):

Does anyone know how to implement the guide line (the green/blue/red lines) on hover and enable the hovermode not just x or y but both x+y?

As far as I can see from here, it only has:
"x" | "y" | "closest" | false | "x unified" | "y unified"