The ability to import data in parallel is now a feature of the new MySQL Shell.  And you can run it from a command line instead of from within an interactive shell.

How Does It Work?
The importTable utility, new on MySQL Shell 8.0.17,  analyzes the input file, divides that file into chunks, and then uploads that data using parallel connections.  This is much faster than the LOAD DATA statement. You get the ability to define how the data is delimited as far a field and lines are defined.  And it works on DOS CSVs, Unix CSVs, TSVs, and JSON if that JSON is in one document per line mode. You also can adjust the number of threads, number of bytes sent per each chunk, and the maximum rate of data transfer per thread so you can balance the load on the network and the speed of data …