I haven't tried it but someone has ported the software, or something similar to Linux. If it works you could get much cheaper hardware, like a Raspberry PI, and be paying much less.
https://github.com/cryinkfly/VCDS-VAG-COM-Diagnosis-system-f...
https://github.com/cryinkfly/VCDS-VAG-COM-Diagnosis-system-f...
I'd look for off-lease corporate laptops, maybe CDW outlet. Chromebooks can work too, but you've got to be careful about specs. Need to be sure you can get a 3rd party firmware, that there's windows drivers for the mouse and keyboard, that there's enough storage (ChromeOS needs much less than Windows, and some Chromebooks are using soldered storage). For modern Windows, be sure to boot from a SSD or there will be much sadness.
Some interfaces present themselves as a serial port (USB-to-serial converter) which Wine may support, but modern Ross Tech interfaces use lower-level, direct USB communication which I don't believe Wine supports.