I own a "harmonium" in my house, which is a smaller organ, which works on air that I pedal.
I also have access to the church organ of my city church, the story behind this is really funny, once I went into the big church when it was very late, and there was no one, I saw on the floor a small harmonium there so played on it, then the priest heard me and let me play on the big church organ, and I can play on it when I want!
But for harpsichords, yes, I know where three of them are. One of them is in my high school (classical music + normal courses high school), and two of them are in the classical keyboard center in Ghent (city close to me), where I go often, and at the end of this schoolyear (around June) I will go there and rent a piano room, and record (video+audio) 10+ classical piano pieces and put them on YT. But yeah, there's also two harpsichords there.
And YES! It's really really funny to try and play Chopin/Rachmaninoff, or Video Game music on it, it's really gay to do!