I'm curious if anybody has attempted to use the bare board Pi Zero (without the GPIO pins pre-soldered) as a virtual Pi on a Pi HAT for a full size Raspberry Pi (2, 3 or 4, etc)? I see the possibility of heat issues, but I think this can be avoided using GPIO extenders or cables. Aside from the obvious micro-cluster, one possible benefit of the setup would be to let the two Pis (Zero + Pi 4, for example) share the same GPIO connected hardware (e.g. power, display, fan) in pass-thru, switch or first-come-first-served mode.
Note that my question isn't about assembling an actual Pi cluster using a purpose-built HAT. My goal is simply to interface two Pis in as simple and compact a form factor as possible without the use of special connectors or layered cases, only standoffs or spacers if needed for stability. Then I could just put the setup in a Tupperware like container along with a USB powerbank.