Any voltage converter is less efficient than just getting another charger.

If this is just to charge your phone, use a device like this.

To charge your laptop, just use the charger from your laptop manufacturer (will be 100-240V compatible) and plug it into the US socket on the above mentioned adapter. Alternatively, get an Apple laptop charger if you want one that plugs directly in to the socket instead of having an adapter brick. Nowadays with USB-C, other laptop brands can also charge off Apple adapters.

Another alternative: let the EU version of the Anker 735 be delivered to your hotel.

FOVAL Power Step Down 220V to 110V Voltage Converter looks like really the best choice, but it is rated to 230W max. Check the max rating of the stuff you need to plug in it, and then look for something similar. It also comes with a EU compatible cable, so you no longer need the Plug Convert to 2-pin EU

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EDIT: strangely enough, ANKER products sold in the EU all seem to support dual voltage, see Anker PowerPort Atom III Slim Wall Charger, Dual USB-C Ports (65W Max) or Anker 735 Charger (GaNPrime 65W) USB-C Charger,

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Advice: if you have the time, and the possibility, return your US devices, and get the EU, dual voltage, version or equivalent - this way, you'll be able to use them anywhere you are, with just some passive plug adapters.