It's possible to create a pure extendscript panel using the floating panel JET mentions, but in order to do this you will have to know the Adobe extendscript javascript, the ScriptUI methods for creating the visual interface such as the dialogs/palettes and then because we're using Illustrator, you will need to use the BridgeTalk object to send the communication between a floating panel and the actual Illustrator application.
Luckily, I've made one some time ago: Adobe-Illustrator/ScriptPanel_2.jsx at master · Silly-V/Adobe-Illustrator · GitHub
The idea is to have a reference to this script inside your startup scripts, so it launches when you start up Illustrator and produces the buttons for your various scripts. The panel works by living somewhere on your network, or desktop, and when the script panel is placed in the same folder and is launched, it will turn all surrounding scripts into buttons and folders with scripts into category sections. Put a nested script panel in there to get a different set of tools to pop out.