Eh, this escaping problem was basically solved ages ago.
If we really wanted to make a UTF-8 data interchange format that needs minimal escaping, we already have ␜ (FS File Separator U+001C), ␝ (GS Group Separator U+001D), ␞ (RS Row Separator U+001E), ␟ (US Unit Separator U+001F). The problem is that they suck to type out so they suck for character based interchange. But we could add them to that emoji keyboard widget on modern OSs that usually gets bound to <Meta> + <.>.
But if we put those someplace people could easily type them, that resolved the problem.
But, binary data? Eh, that really should be transmitted as binary data and not as data encoded in a character format. Like not only not using Base64, but also not using a character representation of a byte stream like "0x89504E470D0A1A0A...". Instead you should send a byte stream as a separate file.
So we need a way to combine a bunch of files into a streaming, compressed format.
And the thing is, we already have that format. It's .tar.lz4!