Not to detract from some of the great suggestions here, but in terms of (code)naming the actual IDP, it's great to stick with something that's company-related. Also depending on the company culture, you can get pretty creative with these.
I recall some of the early Backstage demos about 2 years ago when American Airlines and Zalando did some early show-and-tells: their platforms were "Runway" and "Sunrise", respectively, and they themed them accordingly.
At OfferZen, where I'm at, we're a pretty quirky team from the top down and we've got a number of Lord of the Rings fans, and internally we're always referring to our marketplace as being "middle-earth" (i.e. EMEA) focussed Many of the dev squads and services have similarly adopted names. (e.g. the home page lives in a repo called "Shire" 😄). Our soon-to-be Backstage implementation is currently running with the theme of "Rivendell: a homely place where all great adventures begin..."
Hope some of that helps!