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Here's a seed for a survival island spawn: 5874162437192463513
You start on a very small island right next to an ocean monument. If you don't want to deal with the guardians immediately, there is a small cluster of trees you can punch without getting in range of the elder guardian's mining fatigue. Plenty of wood to build a boat with. Also, a few sheep to give you a starting supply of food.
North of that island only a few hundred blocks away, there is another ocean monument with a mineshaft that runs under it, and to the right (East) a larger island. It's all plains with only one or two trees, but you can bring saplings with you from the first island and get a steady supply of wood going. Animals are sparse, but there are enough chickens that, if you are careful to build up a flock first, can provide a steady food source.
The west end of the island closest to the monument is a good spot to tunnel down and break into a cave system, but if you don't want to dig too much, there are a couple cave entrances further inland.
I've attached an Amidst screenshot of the spawn island and larger island.
Much further away to both the East and West are larger land masses, primarily savanna and plains, if you want to make a resource run at some point.
Oh, addendum for those of you looking for seeds for a How Did I Get Here? challenge, the closest stronghold (1088, -1136) is very close to three more ocean monuments. Unfortunately, the closest nether fortress (728, 728 in overworld) isn't as close, but it's still a reasonably good seed, maybe?