I faced a similar problem. I have now invested my money in an external battery instead to charge my phone if necessary. For me, this seemed like a simpler solution (also, I don't have to worry about a second SIM this way).
For iPhones, there are now batteries that do not even need cables.
https://www.anker.com/products/a1611
https://www.apple.com/shop/product/MJWY3AM/A/magsafe-battery...
They advertise the 633 to hold 1.3 charges for an iPhone 13.
The 622, at half the capacity would only extend battery life by ~60% (not even one charge which is a big bummer)
On top of that, they currently have a $10 discount voucher in the US. https://www.anker.com/products/a1641?ref=select_your_product...
Whereas the EU does not get any discount currently https://www.anker.com/eu-en/products/a1641?variant=415101967...
So that’s $69.99 for the US vs $88.30 for the EU, for the same product.
I think you have a typo there. The product page for 633 says 1.8 charges for the iPhone 13.
I was confused why 60% extra would seem low for half capacity of 1.3 charges (130%). Dividing 130% by two gives 65%.
But since it’s actually 180%, I agree that 60% extra seems low. Should have been about 90% extra one would think.