Mog Kupo (./1) :
I'm wondering how to set the path for binaries in PedroM

Pedrom is far from a complete shell, I not sure there is a PATH system variable

Mog Kupo (./1) :
Also, has development on PedroM entirely stopped now? looks like there's not been a new release in almost 10 years. Was pondering writing a basic interpreter for it (I've previous written one for AVR chips) in order to make it a little more useful standalone but I wonder if anyone is still using/working on it?

Pedrom is not actively developed anymore but the source is available. Pphd (the creator of Pedrom) show up on this forum from time to time. He might accept your contributions.

Mog Kupo (./1) :
Also, side seems to suggest an on board assembler exists (it is configured to call one) but I can't seem to find any sign of it, was this a planned addition that was never released or a third party tool I need to find elsewhere?

side was an external editor designed to work with "as" (68k assembler) and "cc"(K&R C compiler). Side was integrated into Pedrom without these tools, but I believe you can still install them separately. There is also a better onboard C compiler : "GTC", but If i remember correctly it is not available officially on Pedrom (license problem).