I played with both of our Note 8s and several different wireless chargers, and what I'm finding is that our two Note 8s charge wirelessly, and in the fast-charge mode, but only if you get them positioned carefully on the chargers. But keep in mind that we do both have the bulky Pelican cases on them.
With the Samsung "convertible" chargers, I get good charging if I have the charger folded down flat and lay the phone very carefully so it's perfectly centered on the charger. I can't get it to charge with the charger standing up, either in portrait or landscape orientation anymore even though at one time, I did have it work in landscape. My wife has had good luck with hers in landscape orientation. Go figure!
Again, we've both got the relatively thick Pelican cases installed.
I received the Pleson chargers from Amazon yesterday, and they work if the phone is placed in landscape orientation and held up from where it would naturally sit. I cannot make them work at all with the phone in portrait orientation, just like with the Samsung convertibles.
The center of the phone must be placed close to the center of the charger.
To make that placement easy, I've stuck some cut pieces of rather firm closed-cell packing foam onto the chargers with double-sided adhesive tape so that the phones can sit on the chargers, in landscape orientation, and have their centers lined up with the centers of the chargers.
This seems to work every time, and very reliably so far.
The phone claims to be charging in the fast-charge mode, and does, indeed charge rather quickly, even when running the phone, watching TV on it, etc. Of course, things get a bit warm, but nothing seems "too hot". This is very convenient.
Note that you must not only buy the charger, but also a separate power supply for it. They state that the power supply must be QC2 and/or QC3 compliant. The ones I got are these:
https://www.amazon.com/gp/product/B...ag=hawk-future-20&ascsubtag=UUacUvbUpU5993231
The chargers themselves are these:
https://www.amazon.com/gp/product/B...ag=hawk-future-20&ascsubtag=UUacUvbUpU5993231
I can't vouch for the long-term reliability of either item, of course, but they've been working fine so far in the limited time I've been able to test and use them.
Here's how this all looks:

Charger and power supply hooked up.

Phone standing up on charger - Note that it is NOT charging.

Holding the phone in the one position where it charges.

Semi-rigid foam cut to size with cut-out for buttons.

Double sided foam mounting tape attached to charger.

Pressing the foam spacer into place on the foam mounting tape.

Phone resting on the modified charger, charging happily!