Here are some pieces for the harpsichord, though they would also work for other keyboards.
God save The Bull This is a set of variations in the style ish of John Bull from the Renaissance.
Loningdale Jig for Harpsichord A Bach like Jig. (or an attempt at one).
Opus 4 for Harpsichord and Piano This is a twelve tone ish piece of madness from the 1980’s and my polytechnic days. I had a habit of giving all of the pieces an Opus number then, hence the pretension.
Passacaglia Harpsichord A passacaglia in C, which works well I think.