A lot of these are possible with the Direct Control Seat (I refuse to use it's newer name!) and other things.
Though I would like to see the powerups sackbots can't wield useable (grapple hook, jetpack and whatever other ones they can't use), at least equipable so Controlled sackbots can use them.
Not exactly a powerup, but allowing sackbots to go underwater (again, not saying they have to know how to swim, just don't die on contact)
Oh yeah, this one might be doable with sackbots/DCS/etc as well, but a powerup that allows the user to be invunerable to hazards (could be tweaked to decide what ones, and how long the invunerability would last), would work on all hazards except for being crushed.

