I do not suggest doing it, if you do something that I do say here, you're doing it at your own risk.
Well, XPS mobos are quite good. If you have 9550, MOBOs from 9560 and 9570 will fit perfectly. Same goes for 7590 MOBO. The problem? Few screws are placed in the other places, but that's not a problem, since the most important screws are in the good places and it will be placed quite good. Since the whole MOBOs are repleacable, you can have different specs from different generations. You can use even 9th gen. of Intel CPUs and new Max-Q GPUs.
When it comes to batteries, here's the trick. You can use big battery or go for a smaller one and have a perfect place for another 2.5" drive or 2.5" NVMe drive adapter. This 'trick' will work on all of the XPS 15s.
XPS 9550's CPU is limited to 64Gb of RAM(2133Mhz), and the i9 9980HK (maxed- out 7590's CPU) can work with up to 128Gb of RAM(2666MHz).
Screens from 9570 and 9560 fit in 9550 and 9570 screen fits in 9560. The screen from 7590 shall also fit right in in all of the mentioned XPS 15s.
Small thing, but important. Power buttons with integrated fingerprint sensors fit as the repleacement for the non-fingerprint reader ones.
Most of the XPS 15s do have Killer 1535. For Hackintosh purpouse, the better thing is DW1830 or DW1820A. They do work quite good.
The author of this piece of crap is Konrad "Unrooted".