Maelstrom

Ores that the game defines as surface ores will generate surface nuggets - copper, coal (particularly brown) and lead being the most common. Surface ores will not generate more than 7 blocks below the top dirt block. Other ores (like meteoric iron) may generate close to the surface but are not defined as a surface ore. At least that's my understanding. @Streetwind may have more info to provide which I consider more accurate than mine.

Just waiting for those voracious bunnies to turn killer

Sounds like drifter spawning reverted to pre 1.16 mechanics when rifts were introduced as the surface drifter spawner.

In general temporal stability decreases as you descend into the depths. If'n it's slightly unstable at the surface that iron deposit close to the mantle is going to go berserk.

The malachite that spawned about 10 blocks below ground was not defined by the game as a surface deposit and subsequently did not spawn surface nuggets. That deposit likely would have shown up on the density search mode for the prospecting pck though.

Easier said than done, when the only iron for kilometers is in such an unstable area. My first iron deposit (serendipitously directly under my starter dirt hut) was unstable enough that I could dash down to the mine, gather almost 1 stack of chunks before my stability was down to about 20 to 25 percent.

You probably won't be that lucky. My first world I planted my temporary first home directly above a vein of hematite. In my last world the best iron reading I got within 1,500 blocks was a decent reading that didn't spawn any iron. But I had copious amounts of copper, cassiterite, sphalerite and bismuthinite wherever I went. I wouldn't mind that ore generation again on my next world as my last world was 1.17.

In my experience I have yet to fail finding iron on an ultra-high reading. Once I found two ore deposits separated by 5 blocks vertically.

Sounds like you selected the Wilderness Survival setting which defaults to no map. There might be a game command you can enter to activate said map; check the VS wiki or someone else will likely provide it soon.

Battle Jammies FTW!

VS be like "This is the way"

I argue 15% due to drifter spawnage, but that also depends on armor being warn.

A couple of worlds ago I accidently despawned the bee nest about 75 blocks from home. Went traipsing all over the world and closest one I heard was about 2,000 block away. During the following summer I discovered not 1, but 2 bee nests less than 50 blocks from home while clear cutting the scattering of pine trees around my homestead. grrrr...

Bad stuff doesn't start appearing until about 25%. Things get much worse once you get below 15%. I routinely mine until I'm at 25% before heading out. In these situations I make sure I have a direct route to my exit to the surface. If I have heavy armor on (iron or steel plate armor) I may just stick around and slay some higher tier drifters which can provide a huge boost to stability. I think 2 nightmare drifters gives about 70 - 80% stability.

Meh. Before long you'll be swimming in temporal gears and lives become as important as non-hardcore.

Not sure a 4 chunk (let alone 1 chunk) challenge is possible with VS not just due to ore generation but other resources (animals and certain trees among other things) aren't likely to generate with such a small world.

Gambeson armor can be dyed. Just gotta dye the cloth before crafting the armor.

Tree bugs? Well of course there's bugs in trees. Bugs are everywhere! As mentioned, this happens with other blocks. I've seen it mostly when quarrying rock. I prefer to think of the item has an extreme case of Mexican Jumping Bean Syndrome.

On the other side of that RNG, my first world I found hematite directly below my initial, temporary home.

I start prospecting for iron once I have a pro pick. I take it with me whenever I go running hither and yon for other things (bees, limestone/chalk and other resources). I randomly take a reading and record where I get a medium or better reading for future prospecting in finer detail (the grid method in the OP). I ignore any initial readings below medium. So far I've only missed finding one iron deposit which was never better than a medium reading and likely didn't spawn despite the spawn chances. Otherwise, I've triangulated readings to very and ultra rich readings and found iron, once two rich iron deposits separated by only five blocks veritcally..

Only that there's typically a bit of sand next to bodies of water. That sand betrays the type of stone the top rock layer is.

Figure out which blocks are creating the water flow and fill it with bucket and water.

You just need to spend time away from home doing things like foraging for plants (flowers for bees, bees for that matter, seeds, fruit bushes/trees, etc), prospecting for ores, deforesting the local geography, etc.

Sweet! I'll have to look into that mod.

Based on your screenshot and description it looks like you may have let your temporal stability drop to near zero; at which point you experience a personal temporal storm and need to stay in an area of high temporal stability (or murderize a bunch of drifters) until the low stability effects are alleviated. How did you get there? Probably built your home in an area of negative temporal stability and spent too much time at home. While scouting you may have wandered through the area with little impact before you left and what little stability you lost returned. Once you built your home and spent more time in a low stability area the problems began.