At the moment Sales & Dungeons only supports the ESC/POS (Epson Standard Code) control codes, which is still one of the most used control code set. Check if a thermal printer you are interested in mentions ESC/POS or Epson in the description or manual.
In general the rule of thumb is:
- Most cheap chinese thermal printer found on Amazon or AliExpress support it
- Most epson thermal printer obviously support it
- A lot of older Serial printer (like Metapace T-1) also support it
- More specific information about tested printers can be found in the wiki: Printer-Settings