Maybe a MBP 2011 with an eGPU could run Mojave ?
Reading that :
Suddenly I have the question in the title in mind
maybe there is hack possible to get HighSierra compatible Macintosh with an eGPU able to run Mojave.
I installed Mojave on an external SSD, I am giving a try tonight:)
Edit : nope, the computer does not want to start, we can select the bootable external drive but then the forbidden sign : 🚫
Adding your Mac hardware ID to the PlatformSupport.plist would probably work. Find your board-id with this in Terminal:
ioreg -lp IOService | grep board-id