A lot of transverse FWD I4s have a cat or pre-cat as part of or next to the exhaust manifold and have since before OBD2 came out, it’s just ubiquitous now.
I'll defer to your knowledge on that. I grew up building V-8s, but have been stuck behind a desk crunching numbers for most of my adult life. I can still work my way around engines and most cars in general, but my knowledge of the configurations these days is lacking.
The few I-4 FWD cars I've had have had the cat farther down the pipe near where the passenger seat would be. All were pre-2010, and of what I have now, none are newer than 5-years old. The one AWD I-4 I have is much the same. Is this more on performance engines or pretty much taking over all of them?