From the Mac side, I can confirm that a number of the utilities I'm using are straight builds from the Linux sources. None of these exist in package managers (Homebrew, in particular), so I'm having to hunt for the ones that are rarely-used yet still somewhere on the disk that haven't already been mentioned. Note that as I run multiple OS platforms, not all of these are specific to use on MacOS.
lsatr & mkatr - https://github.com/dmsc/mkatr
turbodis - https://github.com/dmsc/turbo-dis
a8rawconv - https://forums.atariage.com/topic/231835-a8rawconv-a-new-raw-disk-conversion-utility/
fujinet-pc - https://github.com/FujiNetWIFI/fujinet-firmware
There are almost certainly others, but, as mentioned previously, they need to be ferreted out.
And on the subject of package managers, I would absolutely love to see some or all of these make it into package management. That's an entire other conversation unto itself, but it would help immensely with knowing what's installed and what isn't. Management, in other words