A pi is a viable solution up to at least a few thousand visitors a day, depending on how spread out they are. You will need to find a way to give your pi/NUC a static IP address though. Many ISPs will give you a static IP, then you can simply set up port forwarding for port 80/443 on your router and be off. If not, ngrok or a similar service can work as well.

That said, unless you have an ideological reason for hosting it from your own home there are many platforms out there that can comfortably fit most non-critical webapps in their free tier with even less hassle than setting up a pi.