In Firefox at least the console offers autocomplete, so you can browse through active variables that way. Basically if you type into console "SugarCube.State.active.variables." you get a scrolling list of everything defined.
I dumped some code parts a few versions back, but most of it is still relevant.
In general, if you're already using the console nothing stops you from opening start_game file itself with something like Notepad++ and just looking through the script for relevant entries. It's no assembly, at least variable declarations are pretty self-explanatory. Especially since Grim, unlike a lot of professional programmers I've ran into, actually uses meaningful names for those, heh, so you can look that up for guaranteed-to-be-current variable names.
Game setup variables (that contain inventory stuff and master stats, along with a LOT of things you shouldn't touch without knowing exactly what they do, e.g. quest states) are below
/* INVENTORY SETTINGS BELOW */
Slave variables can be found looking for
set $girlname = "Lovisa
Though I'll say what I always say when offering such information - the more you rely on cheats, the more you deny yourself actual gameplay, and the faster you'll get bored. I strongly advise to, if you do decide to cheat, keep it to absolute minimum.
Or just don't, and instead of it learn the mechanics sufficiently well that those are no longer necessary. Even avoiding "the grind" will prevent you from experiencing some parts of the game.
