Not that I know of; back in 1.6.4 regular oceans occasionally created small islands where the seafloor went above sea level but I don't think that is possible; anymore in 1.7+, especially in deep oceans, which are about twice as deep and much flatter, as are oceans in general (in 1.6.4 they actually had one of the greatest height variations of all biomes, probably to intentionally generate occasional islands. As far as I know, the only cases of grass in 1.7+ oceans is around the edges of Mushroom Island (ironically, this seems to be due to a bug in 1.7, though I haven't seen enough in 1.6.4 to verify that they do not have grass/ocean biome above sea level). Of course, this is useless if you have a single biome world with no sub-biomes (1.8's Customized allows sub-biomes, including islands in oceans, to generate in otherwise single biome worlds).
Yellow, brown and orange seem to be the only ones where you will be forever reliant on wandering traders for your supply.
You'll need to buy a few cactus, sea pickles and coral blocks to get you started, unless you're in a warm ocean world, beetroot seeds can be found in loot chests or bought from traders, I think the rest can be mined or collected from the ocean (ink sacks).
You can get leather from stolen, tamed and bred trader llamas or from hoglins apparently, though I'd prefer to have some enchantments before going to the Nether.
Last I checked the baby trader llamas need to be tamed within 5 minutes of growing up or they despawn.
And wool can be made from spider string.
I think I might just give it a go myself, last time I tried I spawned at the bottom, way down deep, managed to dig my way into the floor without any tools but got tired of trying to build a tower to get to the surface without drowning and gave up. But if I spawn on the surface and can swim to a shipwreck to get started I can see it as doable.