In general Chromebook and Anker don't overlap as most Chromebook use a round 19V not the rectangular 5V 2A of USB. This is because Chromebooks came out of the laptop approach is a big screen and full keyboard and trackpad and tend to extend battery life via a weaker processor, but still have large battery to give a full typical day for say a student. For example my Chromebook is a Toshiba Chromebook 2 with a 44Wh battery. To recharge it in a reasonably short time it has a 19V 2.37A so 45W round-pin laptop charger, so you see it would recharge the Chromebook in about an hour.
Those Chromebook which do use USB are USB-PD and then you need USB-C cable and then either plug in the battery early and then your 20000 will recharge it slowly, or get the Powercore 26800 PD version. Chromebooks with USB-PD are more wanting say a Profile 2 30W or Profile 3 60W. Your Powercore 20000 is a probably a 10W output so you see the problem in terms of speed. Then the 20000 is likely a 74Wh (3.7x20000) so for a typical Chromebook it would do 1.5 recharges, so you're not going to get many recharges. USB-PD requires USB-C cables to drive the higher Watts.
For camping I recommend a small tablet like a 8" size from Lenovo, Dell, Asus, etc they would be a good fit for a Powercore 20000. The smaller tablets are more typically only needing 2A 5V 10W input and batteries around the 16Wh so the Powercore 20000 would do around 4 recharges.
So its not just port shape, its everything including total power demands and capacity. Fundamentally, a Chromebook is the wrong product for camping.