Splitting zip files are incompatible as a zip on Mac?

When you use the Mac OS command split, it simply breaks the single file into binary chunks, without file type. For example, the Zip file header will only be in the first segment, and the header would be misleading, since it describes the contents of the entire file.

To reconstitute the original file, use cat to concatenate the binary segments back to a Zip file. However, from your question, it appears that would still be too large to work with.

If you need to work with smaller pieces that are truly Zip archives, then you'd need to split the original, 800 GB data* into separate pieces and then Zip each segment. Each piece would be a true Zip file, and could be extracted and then concatenated to yield the original data file.