For disk images, they should be available on Macintosh Garden.
For bootable ones however, I'm not aware of any, so you need to boot from a different disk (e.g. System 7.x) first
Would be interesting to have a method to load or extract the EEPROM data such that it can be used at runtime. Might be interesting for quickly iterating on other PCI<->SATA bridge chips, virtio-blk or NVMe support also.
You can use a ssh client on your Mac if you like coding on your Mac. This allows you to use e.g. retro68 and nano from your Mac.
https://68kmla.org/bb/index.php?threads/ssheven-a-modern-ssh-client-for-mac-os-7-8-9.38593/
Nice I have some bombed boards I could use for ports.
Some additional ideas I'll throw in:
Integrate ram and e.g. zuluscsi on the mainboard
mini-ITX/ATX compatible layout
I'm not sure if RNDIS or USB-ECM drivers exist for OS9, but if they do, you could probably skip the ethernet adapter and just connect the phone directly for tethering.
alloca is usually implemented as a compiler builtin. It allocates a buffer on the stack. There is usually no library associated with it
In a lot of cases you can usually replace alloca calls with malloc / free. And it may be needed if you are low on stack space