Not sure about your actual goals, but maybe start with something like Pico-8 or TIC-80 fantasy computer? Our 8yo son got an instant grasp of the command line this way; I think at least TIC-80 had a handful of standard Unix commands available as well (e.g "ls").

Next thing I noticed, our son was checking wifi availability on his own via 1) opening the command prompt in Linux Mint and 2) typing "ping google.com". Made my day when I saw that.

I suppose the relevant part is to move step-by-step, and to focus on teaching "Unix mindset" instead of specific tools. TIC-80 or PICO-8 are not bad at all for that.

Good luck!