For others trying to find how many charges you actually get from power banks, because it turned out to be not that easy to find, especially with all these variables (see below) and a lot of misleading comments/posts/review from people who are mistaken. Sharing is caring, so please add your devices in comments.

Some thoughts for other lurkers:

• Amper-hours depend on voltage, so 20000mAh (why not 20Ah, god damn marketing and our monkey brains) might differ from power bank to another.
• Watt-hours (Wh) might also be a lie, according to some reviewer even known brands might sin.
• On top you have conversion loss 80-90% roughly speaking.

I bought INIU 20000mah 65w mini P62-E1 for ~50$. It says it is 73Wh. I got exactly one charge 0-100% for my Steam Deck OLED (50Wh) while it being off.

It was as fast as wall charger and thing is small and weights 320g, which is perfect for me. Also design/surface is above what I expected. Included cable is crap and does not support 65w charging, don’t ask me why. Steam deck will on repeat go full charging and then stop with that cable. I can recommend it I guess, but for sure there is something better, depends on discounts, too.