Hey I just bought a fresh copy of GlassWire and are really happy with the software. I would love to see a feature which would be an extension of the firewall.
A deeper insight on the transmitted packets could give a better view about what kind of data (like HTTP/https post or TCP/IP to IP Port) was transmitted (Or when an application first tries to connect to the internet) protocol, in plain or encrypted to find out if it is malicious or trying to send data you do not like to upload.
This would help many malware researchers and people who are working in the security industry I included
Also, some kind of debugger for single packets would be great with some settings like asking for all single packets so you have to allow every single packet and can have a deeper insight when checking the packet itself.