There was a unit similar to the one you describe among the ME3 war assets:
Alliance Naval Exploration Flotilla
IIn peace time, the Alliance's Naval Exploration Flotilla is used as a survey force to chart out new systems. The NEF came under fire in 2185, when several dozen service people were charged with withholding information on rich mining deposits in order to sell the locations to the exploration firm, Baria Frontiers. The Alliance attempted to hide the controversy to little avail, as more and more officers were indicted. Eager to bury its shady history, the NEF has dedicated its entire flotilla and material resources to constructing the Crucible.
Yeah that sounds like something in the vein of what I was talking about, the Jotenheim is is akin to a black project, they test out experimental weapons platforms, mobile suits, etc. Anything from 30cm Tanks that can transform into mobile armors, to prototype concept designs of mobile suits designed as interceptor platforms, that have engines are so powerful that they can literally shake the suit apart if handled inappropriately, to weapons platforms like mass drivers, beam cannons, etc. The unit served throughout the entire one year war but it was devastated in the final months of the conflict when the majority of its pilots were killed fighting the Federation allowing its escaping ships it to survive the final battle of the war at A Baoa Qu, including its commander. Colonel Herbert von Kuspen.
I mean their niche was that despite being test pilots, engineers and alike they were still soldiers, still people who believed in the cause, and despite their unit being the sufferer of scorn both from the enemy and friendly forces they ultimately allow a lot of their allies to escape that final battle through giving up their own lives, and that isn't mentioning all of the test pilots and personal they lost to even get to that point, all of the prototypes they tested throughout the series ultimately killed the people who operated them.
o.o Of course you have the whole...aspect of just who they work for presented in the series, I mean these are folks who work for Zeon back in its golden age. That said the unit story overall to me is inspiring, holding your ground and defending fleeing ships, allowing those vessels to escape the battle after it has been lost. And most of them ultimately die defending their position allowing ships to evacuate, I mean it speaks volumes that the commander of the division(not the ship itself, but the captain's boss) himself was out in the field with his men for that particular mission.
Its funny though that both of these units that sound similar to each other are surrounded by controversy.