Pretty much. It's pretty clear that the versions above are a stop gap (getting pretty damned sophisticated as it goes with those wooden shoes at the end, mind), because when they had the chance, they actually converted the thing in a more "traditional" way, like this:
behold, your new tier 1 German tank destroyer, coming soon to World of Tanks
Being serious, finding some tractor and slapping a gun on the front of it is pretty damned practical; that's basically where tanks came from, after all. You've got a lot to gain as an anti-tank crewman by putting the gun on the front and driving it around that way, like being able to get out of trouble much faster than if you're trying to wheel it around on foot, to say nothing of the out of combat benefits of having it on a vehicle (which can also happily carry you, your mates and your supplies) and the Renault UE wouldn't be the only tractor used this way by German forces. Here's a Komsomolets from later in the war, packing the same gun, with the same more specific modifications than a stick and twine.
That one's really not a bad gig at all for an anti-tank gunner, even if it was done the same way as the Renaults above with the wheels instead of a proper mounting. You don't just get something to drag your cannon around, the Komsomolets actually has a machine gun, for keeping away pesky infantry. This one's a little...uh, under the weather shall we say, so the gun's gone, but you can see the port for it. They're both more "serious" than tying a gun with wheels down on top, but you can pretty easily see how they can evolve. A neat thing to add onto this discussion is that this isn't even just something that you do when you capture tractors like this - the ZIS-30 was built off of the Komsomolets, and the French themselves slapped guns on the Renault UE, giving us this thing on the right.
