Green tunic is harder than wooden sword.
I have done swordless, where you reach Ganon, die, get wooden sword, beat him.
That was easier, to me, than being without the armor upgrade.
At least for Ganon himself, where you get struck by an invisible guy that takes 4 hearts per hit in the Green tunic.
Because for other bosses there are stronger options than the sword (bombs or arrows), or at worst an equivalent to the white sword (in using the magic wand as a club to kill Gleeoks)
A strict minimalist run is obviously hardest of all (wooden sword, no armor, NO WAND) because now you are killing 4 headed Gleeoks with the lowest damage output that can kill them.
And you can dial the difficulty of that challenge by how few hearts you can obtain. (I have made it to Ganon on 3 hearts, no armor, but one hit kills you outright)