GRBL implements a documented subset of standard G-code: full motion and offsets, no canned cycles or macros. The list, the omissions, and what they mean.
The GSK 980TDb speaks a largely Fanuc-compatible lathe dialect: standard motion, G96/G50, G71-class cycles. The list framework, plus where the manual rules.
Okuma's OSP-P300 shares the standard motion core but carries its own conventions: one-shot G-codes, its own cycle and variable culture. The honest orientation map.
Onefinity machines ship with different controller generations, so the honest G-code list is the standard hobby core plus your specific controller's documentation.