Wow! You did a good job compilating special types of companies. I see there the Deathwing, the Ravenwing, the Death Company, the Librarium...
Is there anything for like techmarines or apothecaries?
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The short answer is "yes but".
Yes, the main purpose of the Squires is to produce Troops for other companies but to make that possible they have to enter in combat to harden their recruits, they must serve veterans to learn their ways and take care of a number of rites to keep the Order working. They can do stuff that other companies do but they can still work as regular troopers. In other words, they have a lot of different things to do.
A company made entirely of technicians doesn't feel that way. It's more like some guys in the rearguard waiting for something to break and someone bringing it to fix it.