C41 is easy! It's a fairly tolerant process and I'm surprised people don't do it home as much as they do B&W. It's fairly similar, just one additional step (bleach) and higher temperatures, that's pretty much it - easy.
In fact so is the 3-bath E6 slide process (i.e. Tetenal E6 chemistry). Only the proper 6-bath E6 (Fuji Hunt 6X or Kodak E6 chemistries) can be a bit challanging in "home-sink" conditions, I've done the latter as well, but wouldn't recommend it, much easier on a processor. But a C41 and a 3-bath E6 - easily DIY doable w/o any processor required.
You need a good precise temperature gauge that shows you at least +/-0.2C precision at around +38C. A 5 liter or bigger water bath is sufficent to keep the temperature stable +/-0.2C for the first developer that is the most temperature-critical developer, it's ususally just 3-5 minutes required depending if you push or pull, the rest (bleach and fix) are much more temperature tolerant and you do not need to re-heat inbetween those, I just run the rest off from the temperatre "inertia" the bath holds and never had any problems with bad developing etc, in fact I always get better results then my local lab delivered.
The chemistries aren't that toxic these days as they were before (i.e. formaldehyde is now banned by WW health organisations that was used in the past both C41 and E6), but the smells themselves can be irritating to some, i.e. bleach particulary (that's why they call it a "filthy bleach" in slang, although for me it doesn't smell too bad at least the Fuji Hunt C41 kit I use, at least I'm perfectly fine with the smell of a bleacher). Good thing is that probably your kitchen sink already has sufficent ventilation going (from the above-oven vent, I run it on max) so you probably just barely notice any smells or any at all, just don't work directly between the vent and the chemistries. In case when doing it in the kitchen - throughoutly
clean everything after finishing developing to remove any residual drops of chemistry etc you accidentially dropped here or there - remember it's mainly for making food! (though, for me the film is food too, but a different kind of food). That's it and the results are equally rewarding!
Plus to my knowledge all the common C41 and E6 developing kits come with proper instructions for using them in water bath tampered small-tank developing specifically for the people who do not have a film processor.
I.e. found a random U-tube vid on doing DIY C41: