Hey, not sure how in depth your linux/docker knowledge is. Please disregard if irrelevant. I would recommend you pick a fixed mountpoint for the drive and set up a systemd service to mount the drive for you (systemd .mount file). Then you add an extra line “RequiredBy=docker.service” (look for systemd RequiredBy) This way the drive always has to be mounted by the system before docker is started and should always be visible before you start a container.
Hope this helps :)
I also have a DTSE9 and it’s been on my keychain for at least 10 years now :D
Recently I have just gotten 2 nvme ssd enclosures and have been very happily using them for the super quick image writes. I just checked if there’s some compact 2230 enclosures and some of those even have keychain attachment points… they definitely are a bit bulky for a keychain but I’d argue they still are an option and will look similar to a keyfob :)