You know what since we're taking ideas from other games as an idea for a completely different and unique game, here's a good one:
In Blazing Sails, you have access to a bottle of... some kind of piratical alcohol, and it heals up to 50% of your HP.
What if for a Sea of Thieves' twist, you can drink a grog and while drunk it can randomly refill your HP up to 50% if fully drunk, but this comes at the cost of drunkenness, which can't be fought off as easily even with water splashes.
In PvP it could be a hilariously useless way to get more HP back if you're trying to sink a crew on bananas and fishing bait but need that extra HP to survive any attacks coming your way.
Would be funny getting in a spawncamp where a TSD is trying to double gun me while wobbling around drunk on their heels just because they ran out of bananas to eat on my boat lol