There is no 'JPEG to DST converter' in the same way there's a JPEG to PNG converter. A JPEG is pixels; a DST is a machine stitch file. The transformation between them requires a person deciding, stitch by stitch, how the image should be sewn.
Software can produce a DST from a JPEG — this is 'auto-digitizing.' The output is almost never production-ready. Stitch order is arbitrary, underlay is absent or wrong, small text is unreadable and colors are hit-or-miss.
Professional digitizing turns your JPEG into a machine file the correct way: analyzing the artwork, planning stitch order, adding underlay, tuning densities, compensating for push and pull, and delivering a proof before finalizing.
If someone offers to convert your JPEG to DST in five minutes for two dollars, you're getting the software output. The result may run, but it will sew as though it was auto-generated — because it was.