Consider: (a) locking mouse (b) hiding cursor (c) fullscreen mode
Here's an example if you don't want to search docs: https://mdn.github.io/dom-examples/pointer-lock/
As other mentioned UI needs a few more iterations, but it's ok. I don't think you need to track coins during the run as you don't spend them to buy upgrades - which is not obvious and may require a change in how you communicate things - but on the other hand it's yet another thing tickle your lizard brain and generate additional dopamine boost. A life counter is a must.
Take a look at Electron or Tauri.
This is enough to put it on Steam. In current state it's a very solid freebie, and with some additional work you could charge an entry tier indie fee.