Great work putting the PIC stuff into the FPGA Fabric.
This is great if all you want is a Minimig.
The Idea of the Minimorph Boot Loader is that I can load many different cores into the FPGA.
The ones I am planning for sure is :-
ZX81 (ZXGATE),
VIC20 (FPGA Arcade),
C64 (FPGA64) ,
Spectrum (ZXGATE),
Amstrad CPC by TobiFlex I belive

Atari ST by Wolfgang Förster,
Amiga (Minimig)
This would make the project like the
www.mess.org of the FPGA world

I think using a micro controller Boot loader is the easiest and best way of doing this.
I want to add one platform myself. I will not mention that until I make some progress !
It will be possible to "hand" the MicroSD card over to the FPGA after loading by pin sharing between the micro and FPGA. The Micro controller can offer "Services" to the FPGA, like Tape Emulation, Floppy Emulation, Hard Disk Emulation, Telnet, Serial to Ethernet Conversion, TFTP, FTP, TCP/IP and so on.
I know I can make all this work. In my professional life my work is 90% firmware.
The main thing my work will add to the Minimig is Ethernet.
I would like to order an Altera DE1, is this board OK for the Minimig ??
If you need help with the Z80 firmware I can help there let me know with a PM.
I will port my version of the Boot Loader to your embedded Z80 chip given the chance !