Increase entropy pool by writing to /dev/random (macOS)?

I know there's rng-tools for Linux, but haven't found a port for macOS, so I'm trying to do it manually. I understand you can write to /dev/random to fill the entropy pool (at least in Linux, probably same applies to macOS?). So what happens when you read from /dev/random after writing to it? Is it something like a fifo/lifo-buffer? Will the data read from /dev/random be a mix of system generated pseudo random numbers and what I fed it with? Can something be done so that /dev/random only supplies random numbers from an external source in macOS (I guess rng-tools will do this on Linux)?