Wacky Pc setup? Need advice pls!

Hey so I like... Keep running out of space on my PC XD physically and like TB wise!
I have a 7 TB set up ( I have a few externals gaming HDDs I swap out every now an again, at 2tb each) with a chonker of a graphics card on a tiny ass board XD

None of my build fits in my case (currently running it with the glass door cocked open yikes!) w  my huge fans, graphics card and number of SSDs (i think i have 3 now? or 4?)

So I proposed to my brother, can I just like... connect my Main PC and my second PC? I have a secondary shitty lil windows pc in a ginormous ass case that i use ONLY for VR gaming.

Has anyone here connected motherboards together? My brother said we could do it, it's just impractical and jank. But im tempted to go thru to expand my specs and space.

If you've connected two mother boards and ran multiple GPUs and SSDs this way let me know how! and what challenges to expect!!

Heres my main PCs current specs