No Deno yet. Of course, you can still use TypeScript in the Node.js environment. Though note, ts-node can be a bit slow. If I am using TypeScript (or even JavaScript) for Node.js, I always write my code locally and only deploy the compiled source to the IBM i.
Mocha TN5250 in the Google Play Store. https://play.google.com/store/apps/details?id=dk.mochsoft.tn5250paid
It's $28.99, which is absurd. But, it works well. The free /LITE version times out after like 5 minutes. But you could check it out before you buy the full version.