Launch application from the touchbar
Beside BTT, there is some free option that let you customize your Touch Bar as you like (with the customize widget they provide) and can make iterm2 appear thanks to the dock widget : Pock &amp; EnergyBar 

TouchSwitcher  &amp; Rocket are also a good call as they are only about quick launching an app.

There is also My TouchBar My Rules who claims to be just like BTT, but free ! However it's looks like it's not very user friendly (but never had the chance to try it so far)