Using software already in BAND
You can add plugins to software already available in BAND unless you need them from the command line. Both Fiji and Napari should be able to install/find plugins in your home directory. For example you can install the napari ome-zarr plugin simply by going to the napari menu Plugins > Install/Uninstall plugins. I am not sure how to do the equivalent in Fiji but I am told it's possible. If you know where they look for plugins, you could use your script to automatically download the plugins in the right place instead of going through the whole software installation process.