I was waiting for this question :)

I think it should be quite straight forward but it's more the deployment and maintenance I'm conscious of.

Mac and Windows (to an extent) both have app stores which can handle hosting, auto-updates, etc, though for Linux I'd have to build a bit of that myself. That also complicates platform specific dev / testing / deployment, and as this is a side project I'm conscious of time.

But if there's demand and things go well, I could be persuaded to release on another platform!