That is probably wrong. The manufacturer states that only dual SIM is possible with the Xiaomi Poco X7. Thank you for pointing this out.

Wi-Fi Calling support depends on the specific SIM card and network. The POCO X7 Pro supports Wi-Fi Calling, but it is not clear whether the POCO X7 does as well. The function is usually available if the SIM card and network support it. If you are unsure, you should check the settings of your device or ask your mobile phone provider.

The charging speed of the Poco X7 is 45W. This means that the battery charges from 0 to 100% in around 52 minutes.

If you choose the country Switzerland, it replaces the 2nd Sim.