How to determine if a USB-C power bank can charge my macbook?
If you look at the spec sheet of your MacBook it says that the charger provides up to 29 Watts, which is roughly the maximum power draw the MacBook needs. Now regarding a power bank you would want to have a look at the maximum power [W] output is provided.
Have a look at this article or this quora post where you will find out that the maximum power over a standard (non PD port) is usually with the 7.5W with for USB 3.0. However power banks may offer a USB-C (USB-A usually doesn't offer this) Power Delivery (PD) port, which theoretically can be certified up to 100W, which for mobile power banks usually is out of reach.
From the links you posted, I think options 1, 6, 7 and 9 would work fine.

To say how long a certain capacity will help you heavily depends on what you are doing while connected to the power bank. These power banks theoretically have a much higher capacity than the MacBook, yet this charging system has inherent efficiencies. Also, when you charge the MacBook with this power bank the MacBook will think its connected to a wall plug and then apply the according power settings (so make sure to set them appropriately to extend battery life).
However, I would think you could gain up to a complete charge on a 20000mah power bank. Turning off the MacBook and charging it that way is the most efficient way.

Some ideas on how to estimate the power bank endurance.

Install coconutBattery
Check the power draw at your usual workload

That will give you an idea how fast/if at all your MacBook can be charged (e.g. the newest MBP 16&quot; charger can provide up to 100W and at peak power consumption the MBP can nearly reach that).
Coconut battery also tells you what cycle count your battery is in and how much capacity is left in it. If you then open settings and go to battery (assuming macOS 11.x) you can try to roughly estimate the increased battery life when using a power bank.