the monome-grid library itself is pretty simple; your problem with moving to deno, I believe, is that you’ll also need to port everything related to OSC, starting with https://github.com/dinchak/node-serialosc, but then also its OSC dependencies. And that means you’re into asking for network access, from what little I understand of deno.
I must admit, I’m not a huge OSC user, so my enthusiasm for writing an OSC library for Deno is somewhat low. On the flipside: there are more OSC users than there are grid users, and if you’ve got some OSC libraries, adding a grid-specific wrapper to them will be relatively straightforward.