I agree, Fender’s a fine place to start for maker and budding guitarist alike. They’re certainly my favorite of the most well known manufacturers of late, and there’s a ton of wisdom in their manufacturing process. They’re pretty forgiving to build, with plenty of room to make adjustments that aren’t so easy on some other styles.
With regard to hardware, kits do exist, but they tend to be garden variety pot metal parts and the like. There are some decent assembled wiring kits if you don’t care for soldering irons, and you can find some decent pre-loaded pickguards here and there, as well, if that saves you trouble.
Off the top of my head, the main questions to answer or points to consider before getting started are:
Type of bridge: tremolo/vibrato, or fixed. A vibrato gives access to some cool techniques, but have more mechanical parts, require more setup and an additional cavity, where a fixed lacks the extra ability, but will provide for an easier install/setup/maintenance scenario.
Pickup configuration: Do we want a pair of larger humbucking pickups, a trio of single coils, or a humbucker-single-single combo? There are plenty of configurations and other variations, but these are the most common.
Rough budget, overall, and for hardware and electronics aside. This can usually be worked with at any level, but as with most things, the extreme low ends of the market tend toward things that are not satisfying, and the higher ends suffer from significant diminishing returns. I’ve found a lot of diamonds in the rough at the low end of the electronics realm, but I have a strict policy against skimping on tuning machines or vibratos or advising anyone to do so.
I might also have her point out a few guitars she likes. Maybe try to work in some elements of those makes or builds and/or use them as guidelines.