Not sure if anyone here has seen this, but might be worth a look.
(Removed video link)
Steve
(Edit) oops, sorry, didn’t know it was dependent on running pathpilot on a Tormach machine that runs LinuxCNC!!!
OK, so it’s not a pendant, but this one could be useful, and works with linux/windows/mac.
Turn iPhone, iPad and Android into wireless mobile mouse / trackpad / keyboard with Remote Mouse.
Steve