Hm. I use `rsync -Pa` to copy files around. I wonder how much work it'd take for openrsync to run on macOS. It'd be nice to have alternatives.
An aside, but: the GPL seems to be losing ground more and more each day. I'm not sure whether that's good news or bad news for most developers, but it's certainly interesting to watch unfold. People like BSD and MIT licenses.
Is it losing ground in terms of how many contributions the software gets back? I think that's an important point to distinguish. The big companies, esp Apple, prefer BSD to lock users into more proprietary stuff. We got lucky with LLVM support, but that's partly due to academics, too.
There's plenty more that can be built, though, which smaller companies might contribute their changes to. Especially tech startups trying to get that cheap, community labor tossing some F/OSS stuff out for the community. ;)