Dymo is supported by "Cups" on linux, but it seems to have a few bugs, which can be circumvented.
Printing multiple labels using "lpr file1 file2 ..." can cause queueing problems and jams the printer. The answer is to print each label/file individually, so that each label becomes a separate print job.
In some cases cups configuration does'nt seem to allow setting up the Dymo as a remote printer. This behaviour is a bit unpredictable.
"Qrencode" works well for generating QR coded labels as .png files. Text files can be generated using "Imagemagick" convert or xfig. Difficulty arises when trying to combine multiple images onto a single label. "PNG" files can be combined to a larger png file, but not so well to a pdf file. Combining images of text and qrcode png files to a larger png, and then converting to a pdf using "img2pdf" works with much better image quality and scaling.
"Zbarimg" can be used to decode png images of QR codes.