Along with what Richard mentioned, Dynamics GP Web Client is the closest to an web enabled application we'd have.
That being said, it isn't a fully online application but a way to access Dynamics GP via browser without needing to login to the Dynamics GP desktop application, nor even have it installed on the user's machines/workstations.
You can also setup 'Identity Management' functionality, which will allow users to be able to login to Dynamics GP via Web Client, by only entering their Windows account that has permissions to Web Client and which is tied to their GP user/login.
Using a third-party/external certificate, you can potentially make Dynamics GP Web Client available over the Internet, so users don't need to VPN or connect to the network first.
Let us know if you have further questions.
Thanks