[mattl]

You can run RISC OS on it and then drop down to BBC BASIC within that. I think the MOS is there too.

[pmyteh]

Yeah, you can arrange RISC OS on the Pi to boot up into BBC BASIC V. Much of MOS is in there too, but there are things that changed between the BBC and the Archimedes (and between the Arc and the Pi) so not all code is compatible.

Could probably arrange to boot into !65Host or !BeebEm if you want an even closer similarity, though.