If you run jupyter lab --generate-config and inspect the default config it generates, you’ll see this:
## Supply overrides for terminado. Currently only supports "shell_command".
#c.NotebookApp.terminado_settings = {}
So it looks like you can just about customize which shell will be invoked and how (shell_command should be a list, cf. Customizing shell launched by terminal), but I don’t really see an option for having multiple tiles for different shells in the launcher 