Thanks! That is definitely a good piece of the puzzle to find. I also found this,
which allows you to change the shell used, but probably not on a per-launcher basis. The “shell” could presumably be bash with some options to run a startup file which was the command I need. But can this be adapted to choose the shell based on which launcher was used? The terminal functionality doesn’t seem well documented, or is maybe just very focused on doing one thing well (allowing an ssh-like login to the server).