It looks good, but there doesn't seem to be a desktop version. If this is using a JS framework, you know, like React or Angular or Vue or like that, you can just slap Electron on it and you'll be good to go on all platforms.
Maybe you can add a feature where a the compiled script can run on testnet if you deposit a small amount of BTC for the transaction fee. You can make the outputs 0.
Great idea! will definitely add an offline electron version in the next release. Also right now we are working on a 1-liner that spins up a clean regtest network in a docker container with funded wallets and automining so you don't have to mess around with faucets, but testnet integration also makes a lot of sense.