PupZi Guess not, unfortunately I do not own batteries below 12V to test. But a voltage level below 10V is not healthy for a 10V accumulator so you better look for a more specific one.

PupZi Hi I personally don't use the switch with the original firmware. But with tasmota there is no restrictions.

PupZi Probably,I personal use it on my Dell Laptop (in blue mode) and on a Samsung Tablet (with green mode).

PupZi Si,il tensione al' entrata 'diZ J

PupZi it should - for example tim and Vodafone uses the European standard. You only have to know the APN, username and password of your provider. Dail number is *99#

PupZi In short -> NO! General IoT devices uses 2.4 GHz WiFi standards (802.11*). Reasons may are different but mostly because of the ratio of coverage by sending power. In IoT then maximal data throughput is in most applications less important rather then a stable radio reception. This device (POW R2 AC90-250) is based on an ESP8266EX chip. As documented in the Data sheet the chip is designed for 802.11 n support (2.4 GHz), up to 72.2 Mbps.