Is it possible to toggle Resource Pack elements for players?

Context: I want the appearance of the armour bar to change with the armour material equipped
Alternatives: 

Using a display entity with interp for this element in Paper/Spigot and modifying it, while hiding the HUD element entirely with the resource pack
Using the XP bar, etc. (other components) for this as they won't be in use
Switching the resource pack entirely for the player ❌ Bad solution

Requirements:

Without armour, no armour bar is shown ✅ Vanilla
With iron chestplate, the armour bar is blue
With netherite chestplate, the armour bar is orange with a different number of icons (same "progress"/"size")

Using:

Paper/Spigot (so a solution relying on these is ideal - but a generic "method" is even better!)