I've been this close to building my own version of something like this, multiple times over (and actually built a browser-based one as a way to learn .net core when that first started), because - like I said - it's a really handy utility.
But I could only justify paying for something premium, like wide area sharing or torrent-like sharing for faster and resumable transfers. To get a file from one device to another can be cumbersome, for sure. But a cable and and an adapter would cost less than your solution, and have benefits (and drawbacks!) of its own. So I just couldn't figure a subscription* for something that, in the worst case, is a tedious pain to set up myself and in the most practical case is replaced by a simple, if cumbersome, process. Maybe others are doing different calculus on this (everyone has their own threshold for 'too much hassle' or 'not accessible enough'), but it's a pass from me without free local sharing.
*not sure what's 'free updates for a year' would mean other than "you will need to pay another $19, to continue receiving updates" which is a subscription, by my definition.