I'm doing something similar but with slightly different RAVPower products.
https://www.amazon.com/gp/product/B082PGS78L/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B07TC53ZYD/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1
This combo weighs about 200 grams less (I onebag travel a lot and try to keep things light). Still (allegedly) provides 9v/3a. More critically, after coupons I was able to buy it for $58 which is less than half as much for 2/3rds the capacity. Great deal. They come in on Friday, excited to try them out.
The GPD Win 3 needs a PD-compliant charger that supports at least 15V/3A or similar 20V output. (PD 2.0 or higher)
The Anker powerbank you linked to doesn't really list all the details needed, I couldn't find it on their website either, so I can't give you a definitive answer to whether or not it will work. Although I'd assume it will, since it lists 65W output.
However I can tell you that something like this should work fine: https://www.amazon.com/dp/B082PGS78L/
I use this one and its been solid: https://www.amazon.com/Portable-RAVPower-20000mAh-High-Capacity-Compatible/dp/B082PGS78L/
Hooked into a 15.6" 4K touchscreen monitor, then USB-C from monitor to my phone (Note 10+) I get around 4-5 hours with the monitor brightness around 50-60%.
I ordered this:
https://www.amazon.com/gp/aw/d/B082PGS78L?ref=ppx_pt2_mob_b_prod_image
It will arrive tomorrow. It should work because it supports the right standard and voltages, but I'll report back all the same when it does