No MIDI in for the moment. It’d be nice to have, for sure!

For learning - I agree - I wanted to have some kind of ‘difficulty’ heuristic for pieces, and recommend easy ones. I just haven’t been able to come up with anything yet.

You can look up the royal grading the UK uses for classical pieces and use that.

A single difficulty score is a bit difficult (hah) as a piece will have many technical dimensions to it, and ideally you're comfortable with most of it but a few dimensions push you out of your comfort zone.

I think these standard grade scores attempt to give some kind of loose ordering to when you might want to tackle the piece.

I'm actually from the UK. Is this the grade system people normally refer to - like they say they're grade 8?

I meant more an algorithm to determine the difficulty. Things like tempo and how much your fingers would need to move. But equally, I could probably just cherry pick some easier pieces far quicker

Synthesia works with midi(via USB) - at least the PC and Android versions do.

I use Synthesia on the iPad and it works great.