"Embarking now" gives you 2 axes (random material), 2 picks (usually copper), about 60 units booze, and 50 units meat, plump helmets, and the like, and 1 anvil.
Its toady's generic embark profile. It's good enough for most embarks, but not well suited to "extreme" ones. (Though using it on such embarks can be FUN!)
It isn't the same as doing a custom embark, and unselecting everything.
(Though that could be quite challenging too... theoretically, you could possibly survive that if you had access to trees. Dismantle the wagon for 3 logs, use one to make a carpenter's shop, and then 1 to make a training axe, then use the training axe to cut trees. Use wood floor over a clay deposit to expose a bare clay patch, etc. You still need 1 stone boulder to make a kiln to do the collect clay job, but after that you could do clay surface construction and NEVER dig. You could possibly get that from the trade caravan using a wooden trade depot, and trading wooden goods.)
But, here's what you would need to survive an "everything unselected" embark challenge:
Heavily forested temperate biome with abundant surface crops, shallow minerals, non-terrifying, non-savage.
Step 1, disassemble wagon and make a food stockpile.
Step 2, assign an herbalist, then mass designate collect plants.
Step 3, assign a carpenter, make a carpenter's shop from 1 of the logs, make a training axe
Step 4, assign a woodcutter, cut trees, designate lumberyard
Step 5, make barrels and still
Step 6, make a bowyer's shop, make crossbow, make wooden bolts
Step 7, assign hunter, turn him loose
Step 8, make butchershop and tannery
Step 9, assign butcher/tanner.
Step 10, make leather armor and crafts
...
You get the idea. Use the trade caravan and a wooden depot to get essential equipment.
After that proceed normally.
The starting equipment just helps you get to a level of stability quickly, and that's it. Same with starting skills.