If I remember correctly one cannot change the keybind as it will always be enabled even if you hide the text at the reticle. I think there was no way to overwrite this kebyinding without destroying it for all the other "Use" cases.
One maybe could block the interaction like blocking some action bar skills was done if you are not in fight (to suppress necromancer skills in cities e.g.) but I think it's different and there is no real similar way to achieve this with keybinds for the reticle stuff.
Perhas one could hook into ZO_Reticle:TryHandlingInteraction (but I think GetGameCameraInteractableActionInfo() does not return a dedicated value like "I'm asking for interaction with a companion" so one would need to check the companion's name below the reticle... Hacky solution with much manual effort to keep companion multi-lingual names, and new ones, updated :-( (
https://github.com/esoui/esoui/blob/...ticle.lua#L133) and do some checks there, but I think I already tried this in the past and the work to achieve the wanted would have meant you need to overwrite SO MANY code lines, and assure all addons stil work, other/new addons need to be adopted etc.... This was way over the top.
Accessing the companion by other menus is not availabla s you MUST inetract with the companion, else the scenes and all stuff like equipment of he companion, skills etc. are "read only". Mans you can see them but NOT use them.
I already tried to add this to my addon FCOCompanion in the past and ZOs told me there is no other way then talking with the companion -> means the interaction is mandatory!
I guess ZOs should just allow to define the same or another keybind and you should ask in the official ESO forums for that.
The more will see it there the more will like the idea and ask for the same, I bet!
But addons are not really able help here, afaik, sorry.