The shoebox compressor is designed for people in remote locations and is only a booster so you need a compressor to start with, not a tyre compressor but a workshop compressor that can give up to about 100psi and for prolonged periods. In the video below it takes about 2 hours to top up from 4000psi to 4500psi
An alternate to the shoebox is a stirrup pump, but also takes time and a lot of effort
With both of the above you also need a filter system to ensure the air is clean. Paintball cylinders need air clean to breathing standards, any contamination from the compressor or pump can cause failure - if the cylinder gets hot when used on a paintball compressor later there is a real risk of explosion from contamination.
A realistic option if you do need home fills is a scuba cylinder and fill rig. Get it filled at dive shops. But you are still looking at hundreds.
If you just want some air for home testing then make sure you have filled the cylinder before leaving the site, and optionally buy a spare cylinder or two