mITX builds are done pretty much backwards. With conventional ATX you pick any case you want, any cpu, any cooler type, any gpu, any psu etc and just toss it in, very little regard for actual space or limits. Some might quibble over big air use in slimmer cases, but no worries, just use an aio or different air cooler.
mITX is the opposite. Pick your case, sure, then start shopping. Brand, design, performance, all that takes a back seat to size. The smallest cases can only handle the shortest air coolers, such as a Noctua NH-L12 or in many cases even that's too tall and you'd be looking at a Reeves instead. Which means you won't be running a 10900k or 11900k etc, and if you do, it's going to be severely throttled thermally. A 3090 FTW or other 3 slot card? Forget it.
My mITX was reduced to finding components with MM of clearance, which meant using certain components, regardless of my wants or desires. But the end result is a full cpu/gpu custom loop with 2x 240mm rads in something the size of a shoebox. Took 6 months and more of planning, testing, researching, designing, starting over, beginning again.
It's mITX, be prepared to think like a woman and change your mind a hundred times per component, just because it simply will not work as intended.