I also find VisiData is useful for adhoc exploring of JSON data. You can also use it to explore multiple other formats. I find it really helpful, plus it gives that little burst of adrenaline from its responsive TUI, similar to fx and jless mentioned.
For my toolbox I include jq, gron, miller, VisiData, in addition to classics like sed, awk, and perl.
[1] https://jless.io/