All the devices you mentioned charge via USB, so really all you need to do is carry a USB wall adapter, that is compatible with USA / UK voltages.
I carry with me a macbook pro lightbar 2016 wall charger:
Easy to adapt to any wall adapter, since it comes with multiple wall heads and these are easily found in most local shops.
Has universal voltage support.
Has a removable USB cable; which means I can plug in (with a suitable adapter) any USB cable to charge any kind of device.
Supports "fast charging" on mobile phones that support it, since it has a higher amperage output.
I am talking about the 87W adapter (link at apple.com).
The good news is that from the last 5 years or so that I have been buying gadgets, all the chargers that I have bought - including laptop chargers with USB ports, cell phone chargers, smart phone chargers, wall adapters, multi-plug ports ... are all dual voltage.
If that fails, you can always charge those devices from another USB host, like a laptop or desktop computer.