I just found few wireless chargers for Pixel 3 and 3 XL. Also got to know that Google is working for fast charging compatibility with third-party qi wireless chargers.
Here is data from a test of Q1 and Pixel stand, and a Q1 phone and Pixel 3. Although not truly definitive, it supports conjecture that
1. Pixel stand will fast charge Pixel 3.
2. Pixel stand will NOT fast charge Q1 phone.
3. Q1 stand will fast charge Q1 phone.
4. Q1 stand will NOT fast charge Pixel 3.
As Pixel is using Power Delivery (PD) standard, this data is consistent with that. Also, both the Pixel 3 and the Pixel stand are compatible with the BASIC Q1 standard of 5 watts maximum.
Google is licensing outside vendors to supply compatible chargers, but undoubtedly these will fast charge on PD systems ONLY, as the Pixel stand does. In light of this, I would seriously recommend paying for any Q1 charger, as shown in above "list", if you are expecting to fast charge a Pixel 3. Unfortunately, the Pixel 3 will lie to you by displaying fast charge on Q1 stands , but it will NOT fast charge!
Sent from my Pixel XL using XDA Labs