Just buy it. Don’t think. Just buy.
This is the one you should own, at least one of them. Carry with you when out and never a flat phone, fits in winter jacket pocket easily. Even if you don’t have any PD devices, this recharges fast because of PD. Combine with a Nano, and if you have old technology phones like iPhone then add a C-Lightning cable to get 18W recharge. Then a complete system to last a very long day and recharge fast overnight.