As you undoubtedly have already suspected, there is a lot of snake oil in the industry of sound.

You are correct: there is a major risk when you buy pickups (or a guitar, or an amp, etc.) without knowing what effect it will have on your instrument / setup. The only definitive way to know is, of course, experimentation. To this day, I am not aware of any selling point or service that will allow you to e.g. install a pickup in your guitar, take it home for a week, and see what you can actually do with it. This is where the snake oil sellers come in:

• YT videos containing a meaningless flurry of licks as if coming from The Pickup. The reality is probably closer to a host of effects after a modeller - oh, the pickup is not even selected, so you're actually listening to Yet Another Seymour Duncan Pickup.
• Tone that is described in vague terms, or terms that have nothing to do with the sound. Ceramic pickups, pickup trucks, crystal sounds, icy sound, bright sound, aggressive sound, active sound. Do you get the - flaming hot ceramic - picture? I mean, whatever happened to actual listed frequency-output values? Are they even in a pickup's spec any more?
• You either want "metal" sound, or "vintage" sound, or "classic"...whatever happened to uniqueness, it doesn't fit in the labels which are the object of their own mass-production line.

I'd urge you to ignore all those. I think we, collectively, need to put more emphasis into evaluating - as such, either try to evaluate pickups before you buy them (on another instrument? borrow from a friend? evaluate on a solid and quantifiable measure like frequency output relative to other pickups?) or buy as cheap as you are comfortable with.

PS. You may find it useful to leave effects & amp characteristics out of the way when comparing pickups (as in, play & listen clean - not unplugged).