No picks is feasible if you settle on a cave in 1 cavern world, or multiple cavern world with downward passages or chasms connecting them. Might need to hack/do initial dig of connecting all 3 caverns, and possibly sea and hfs below, to the surface.
Could even be fun to settle on a kobold cave with the update.
I'm not sure where axles are necessary in lieu of rollers of gear assemblies, but both windmills and water wheels require wood to build, so it'd mean being dependent on caravan for imports. Though not much of a dependence; don't need that much power after all.
Therefore, no woodcutting/no axes should also accompany no trading - maybe do that with dead civ and everyone else at war with you. Beds can be obtained by moods and everything else can be made from aluminium.
Hm, pair that "no migrants" condition with creating adventurers of, retiring and marrying off two pairs of animal men. Could be neat to see how long till the last dwarf in the last dwarf settlement on war with all sides dies.
The alcohol from meat is kind of neat, but kinda defeats the point of the challenge in no farming or plant gathering. It's like deciding to do a game without forges and then having ash+bone or superwood armor and weapons that are structurally equivalent to steel.
Though that reminds me of something I saw on the scenario generator - settle on a glacier, everything must be built above ground.
Can do aboveground farming in there with air biomes, but OTOH no water. Still, once that is done the challenge is not much. Unless there's fundead birds in air, which would make settlement and expansion harder.
Initially interesting idea - how about aboveground settlement, no walls or gates, traps or anything blocking line of sight or substantially movement i.e. basically enemy army can see dwarves from any direction they approach from and then don't need to divert their path and can walk straight to them.
Wouldn't stay challenging, though, past certain point it is "just send in the army". A sense of progression could be given if only gear permitted is ones taken off visitors or invaders, though that's pretty much "no forges 2: don't forge harder". Maybe just using foreign weapons in military exclusively?
There's the old vjek's challenge embark to Pseudo, the core of which was deadly hot, deadly rain, reanimating, no water or metals on map. dry caverns and no magma sea. It'd pretty much trivialize killing sieges, though, unless they're fire-resistant sieges.
One more, I guess, though this doesn't appeal much: Try to fulfill what the diplomat asks for like Atolaslob. For every unfulfilled request, fulfil dwarven justice and execute the dwarf with the highest skill in labour that could have produced the request.