Kinda interestingly: it zips to 17MB, but the binary looks to be 56MB (davit.app/contents/macos/davit). That seems like a surprising amount of compression for a binary - embedded assets maybe? Possibly this is normal for mac apps though?
But that's just "noticed", I definitely haven't paid much attention. And don't have a mac nowadays, so I can't go check my hard drive now.
Localization files compress well, compiled code compresses well, repeating assets (@1x, 2x, 3x) and the pair of binaries in a universal app (x86_64 + arm64) do too, etc.
Ah, and dmg compression is just LZFSE, zlib or bzip2, so pretty standard stuff as far as I understand it.