Would love to see this as a more difficult version of the traditional "no kit" kit.
I can think of an equivalent where only leather armor is the maximum armor and stone swords are the highest weapon you can use. Still has 10 hearts, but cannot use iron+ swords or gold+ armor. This should be about the same effective HP as one would have at full iron with 5.5 hearts.
I'd also love to see it as a competitive kit gamemode where only that kit is equipped or just up to leather + stone swords, no higher armor/weapon tiers.