Yes, you can use VSCode with Serenji for editing GT.M and YottaDB sources. Debugging is not yet available.
Once you have installed the Serenji extension you just need to configure VSCode's file associations so that .m files are registered as "ObjectScript INT".
You can do this by editing your settings file, as below, or via the VSCode user interface.
"files.associations": {
"*.m": "intersystemsobjectscript-int" }
Doing this will give you syntax colouring, some intellisense, and features like F12 (Go to Definition) which can be used to follow code references.
I expect futures update will add the .m file association automatically, and have more GT.M/YottaDB specific functionality.
George