Found a fast charging power bank (battery) at a low cost for the Mate 9

[chanchan05]

One more thing to note:

I have since tested this with my Pixel 2 XL.

It does state on the phone that the tronsmart pack "charges it rapidly" but the Ampere figures are lower than I thought they should be.

Not sure of Ampere works properly on the Pixel 2.

Does pixel 2 show the time estimate? Samsung devices do, based on the rate of incurrent. You can base off that instead.