That’s sort of how I’m understanding it, they’re talking about the build process specifically and want to re-base their toolset to BSD/Linux. Not sure what their current build process entails but like you said it could be they’re currently stuck with some sort of proprietary / Apple specific software.
Yup there’s at least a few projects that can do in browser file transfer using WebRTC e.g.
https://sendfiles.dev/
https://sharedrop.io/
https://github.com/kern/filepizza
And of course https://github.com/magic-wormhole/magic-wormhole (they used to have a website too but maybe that went away?)