I guess it would be somehow possible this way, without having to know what potion "exactly" you are currently trying to use:
You define which potion type is slotted at what quickslot number via a settings menu.
e.g. slot 1 stamina, slot 2 magicka, slot 3 health, slot 3 tri stat
As you use the quickslots one could then check if the current used quickslot is slot 2, so check if your current magicka is below a threshold value, allow the usage then.
Not sure about the "allow the usage", if this would be even possible to "block", react on the double press key thing you had proposed, and if this all can be checked performantly. But this would be the easiest thing that comes into my mind for anyone wanting to try making that addon for you
Code of quickslot settings LibAddonMenu-2.0 menu can be spyed in my addon FCOStarveStop -> a dropdown box where the slotted quickslots are shown in and you are able to select one (please just give credit if you do so guys!) and the block of skills is e.g. handled in the addons that block necromancer skills out of combat (as the quickslot is a skill slot too somehow, or at least an action buton) -> LibSkillBlocker used in e.g.
https://www.esoui.com/downloads/info...ecromancy.html (also credit where possible and if used, even if only spying code or ideas!)