I wanted to do that too so i gave myself a oak sapling, berry bushes, cattail, a wooden pan, flax seeds, cabbage seeds, carrot seeds, a quern, a crate full of limestone gravel (aroud 1300) and some water/lava. You can get flint from gravel for tools, clay for pottery, copper for tools, clear quartz for windows and maybe a occaisional bronze armlet (Or if you are as lucky as me, you could also get a temporal gear before piece of clay). You can also turn on rifts for extra annoyance. To get grass for pit kilns, torches, beds, roofing, firepits of haybales, you have to break and then replace the dirt because grass doesnt grow on naturally generated dirt in superflat worlds. With this you can also make a straw dummy from two haybales and a stick for a friend. For buildings you can use rammed earth if you dont like dirt houses. I dont recommed eating in early game because it is really rare. Just play until you run out of hunger, clear your inventory and kill yourself in lava (dont forget to drop the reed baskets!). I personally did this on my steamdeck because panning is a great thing to do while you are e.g. on a plane. Woud be cool if someone expanded this with more ideas.