Using AMS colors in standard cards

[isketch93]

Hi all!
I recently began my journey with HA, and am now learning to cobble together my first custom dashboard. I stumbled upon HACS along the way, and this lovely integration soon after (which I am loving, by the way).

However, I got stuck on a small hiccup, of which I could not find any mention online. This usually leads me to believe I am missing something either very obvious, or not strictly related to the subject at hand, and this is where I come asking for the help of those who are more expert than me.

I will keep it short: I'm trying to put together a simplified overview of the AMS using mostly default cards, and I'm failing at rendering the spools' icons in the correct colors.
Through trial and error I found that this parameter is indeed available: in the following picture you can see I get a hex code of the correct color, since the spool is white PLA (every slot reports the correct color):

However, I am not able to extract it to use it in any other place.
For example, I settled on a grid with 4 mushroom entity cards in it, but no matter what I type in the icon_color field I can't get them to show the corresponding spool's color:

(that icon_color: color is admittedly pretty naive, it is there purely for demonstration purposes)

I even tried to reverse engineer the examples found at the suggested page to find the correct syntax, to no avail. I would appreciate any help on the matter, it is obviously not an urgent matter, but it is driving me a little nuts.