DB48X: HP48-like RPL implementation for DM42

[bdb]

I've discovered this project last week. I've read the whole thread. I've watched some videos. This is amazing! Exactly what I like to use.
A few questions (apologies if I missed some answers given before):
- am I understanding correctly that the code for interfacing to the DM32 or DM42 (let's call this hardware abstraction layer) is decoupled from the calculator "application" itself?
- if so, is it possible to modify DB48X to run as an REPL (read eval print loop) in a terminal?
- would it make sense to port the work of B. Parisse (Erable/XCAS) on DB48X?
- how much faster would an HP Prime G1 or an HP50g be? I don't know the microarchitectural/instruction per cyle differences between the ARM processors of the HPs and the Cortex M33F/M4 of the DM32/42.
- finally, what would be the ideal keyboard for a purpose-built calculator? (An Android version could help try with different scenarios).