The jackhammer currently acts as the ‘key card’ of choice in many end game areas, granting a very easy way around most of the later game door/gate/hacking obstacles, and doing so quickly.
It should really take quite a substantial amount of time/batteries/gasoline to burrow your way through concrete walls (say, 15-30 min) and even more for the steels walls of bunkers and bank vaults (e.g. 1-2 hours). It should also generate enough noise to substantially deafen you without ear protection.
Pickaxe would presumably generate a bit less noise (but still a lot) and drain a ton of stamina and take substantially longer to dig, based on STR.
If you mean a small electric motor, those can be crafted with copper wire and some scrap. The electric jackhammer is usually pretty easy to make by the time you might need one. They’re fairly common in hardware shops too.
True, but a midgame character only needs midlevel computer/mechanics skills to break into a bank and get lucky enough to find the quantum tunneling CBM, then basic first aid skills to install it (and lots of luck). That will get you anywhere.
Electrohacks are pretty simple too, just a little more skill to do the actual hacking.
There’s nowhere in the game that’s overly difficult to get into. The hard part is surviving whatever else is in there. Which, usually, means a control laptop.