I would say the general invention of something that would be in the very general category of "computer" would be kind of inevitable. Also knowing a bit about computer history in Germany, I wouldn't say that they only existed...
Hélène to break Nazi Germany's cryptography during WW2
We could either way blame the invention on maths people. For example, Babbage's Difference Engine was invented long before even the first World War, in 1822 according to Wikidata. And I guess there were also lots of mechanical calculators, though the need for those was probably more for business and (circling back to military) ballistics calculations, but probably also - to a lesser extent - for scientific use of course.
Konrad Zuse started with his first models for a computer in the earlier Third Reich times as a mechanical computer (Z1). It's unsure if the original machine ever really worked because it was destroyed in a bombing attack.
I'm not a historian, trying to cobble together some bits from Wikipedia. It seems that Zuse tried to get some funding from the Wehrmacht but they turned him down because it would have taken too long. As far as I can tell it was more of a research and/or passion project of his.
I guess at some point, computers in general would have been made electronical too. Like I said it's unsure if the mechanical Z1 ever really worked and even if, it was incredibly slow and cumbersome to operate. The suggestion to make it electronical came at some point and the later Z3 used telephony relays. (Side note: Z3 was "released" in 1941, Colossus was "released" in 1943, so technically Zuse was first?)
So I would say the interesting question is, how would computers and the technology we built with them look today, without military involvement. I mean I guess the Zuse ones are the closest we can get to that but they stopped at some point and got overtaken more or less. But for example the Internet itself started by the military (ARPA) so I guess things could look quite different, though I have no idea how. Perhaps we'd all be using Fidonet or something like that. (^_^)