It's a great question. We understand that billions of people use Windows and Android, and they're both great platforms. Both platforms have advantages over Apple devices in some contexts, and both give a greater choice of hardware, customizability, and so on. However, for now, we haven't gotten any movement forward on bringing MIDI Designer Pro 2 to Android nor Windows. We're an entirely bootstrapped, 100% developer-owned business. We explored doing it ourselves, which we cannot afford (even to get to MVP). It's also high risk since we have no experience selling on Android/Windows, and have come to understand that it's harder to make a market on both of those platforms. We also explored getting a partner on board, perhaps to pay us a licensing fee, but with no luck.
We're open to the possibility but for our current 1.5 year roadmap, we're not envisioning coming to Android nor Windows.
It's worth noting that you can often get an iPad that's ideal for MDP2 for as little as $99. We're recommending an iPad Air 2 or better at this point.
Thanks again for your interest, we hope you'll understand our situation.