How can I know the progress when importing data into MySQL using LOAD DATA INFILE?
Sort the incoming file by the PRIMARY KEY; this will speed up the LOAD.  Don't have any secondary keys during the load.
There is no way (that I know of) to watch the progress in 8.0.
The .ibd file size is not a reliable indication -- you can't easily predict how big it will eventually be.  Datatypes, data values, PK, other indexes, etc, impact the size.
Also, that file will grow in bursts.
Having just two BIGINTs (8 bytes each), the table might be about 40-60 bytes per row.  The smaller range might be about right if the data is in PK order; the larger if not.
I hope the query does not timeout.
The process is probably I/O-bound, indicating that nothing you could do would speed it up.