I don't believe the Vaporesso Target 100 has TC. It also may not have step-up (no buck/boost, only buck). Newer mods today, even if the same size or smaller than the Pico 75W, have no TC and many have no step-up.
As far as tube mods: in my opinion, an 18650 tube mod isn't really "smaller" than, say, a pico 75W mod because while it's obviously slimmer, it's also a lot taller. To me, that makes it "bigger" and also awkward in the pocket as well as on the desk (top heavy).
I don't think you can get much smaller than a Pico 75W in a TC. There are a couple mods I know of that you can still find that are smaller than the Pico 75W, but they don't have TC: Eleaf Istick 10W, 20W, 30W, 40W and the new Istick 2 (no step-up or TC on this one).
The smallest mods I know of with TC are...
- Vaporesso Swag (about the same size as Pico 75W but feels smaller, not easy to find at a decent price)
- Vaporesso Swag II (really light because everything that can be plastic is plastic)
- Think Vape Craton DNA 100C 100W (21700)
- EHPro Cold Steel 100 (but VERY heavy) (21700) (kind of like a tube mod with the electronics on the side instead of on the top, making it short)
- Eleaf Pico 25 (just barely bigger than the Pico 75W but good luck finding it)
- Vaporesso Armour Pro (good luck finding it)
- Eleaf Invoke (dual 18650 mod, but tiny as hell - no step-up - good luck finding it)
- Eleaf Pico Plus 75W TC (I don't believe it has step-up and cannot be flashed with Arctic Fox)
- Eleaf iStick T80 3000mAh TC
- Ambition Mods Converter
- Cthulhu Hastur 88W
- Vapor Storm Puma Baby
- Geekvape Aegis Solo
- Geekvape S100 (aka Aegis Solo 2)
- Asmodus Colossal
There are probably others, but these are the ones I know of.