Is it hot?
Computer chips typically run at a much higher core temperature than we would expect. Most of a chip is actually a heat sink as all the power consumed by the chip ends up as heat and has to go somewhere. Large surface area to disperse the heat, and that will mean a lower surface temperature than at the core.
What you end up touching is the outer case of the unit which will be cooler still.
Is it accurate?
I suspect that the temperature reading for the shelly devices is actually an on-board sensor, just part of the chip circuitry. Chips these days come with everything built in. Therefore the reading is the core temperature of the immediate silicon base. Is this accurate? Maybe. Temperature sensors are usually either thermocouples or a temperature sensitive resistor/thermistor/diode/transistor, and all of these devices and associated circuitry only read relative temperature. Accurate temperature measurement requires a second reference point - ideally something like melting ice in water. Without this such devices make a guess at the reference point. A quick search on the web suggests Shelly monitoring devices are accurate when compared with other devices for ambient temperature, however for the encapsulated power switch devices checking accuracy is probably not that easy.
The base circuit will probably run on 5 volts, the standard for logic chips, but of course Shelly power devices are wired into the mains 230V AC and this has to be turned into 5v DC. No transformers these days but certainly some pulse width switching and a fat capacitor and some resistors, all of which adds to the heat. Power measurement requires voltage sensing across a resistor, so yet more heat. Also they are WiFi enabled, and I wonder if the power rating goes up if the WiFi signal degrades.
Does it matter?
Only if the chip starts to fry. I’m guessing anything over 100 deg C might begin to be an issue, but hopefully Shelly have used good quality components that are designed to carry on working at these temperatures. Up to 200 degrees, aparently, for quality components that are designed to run hot. I have a shelly switch installed in an outside socket which I use to measure the power consumption of my hot tub in the garden. Not used to switch or do anything else, just report the power used.
Here is the temperature graph for the past 10 days, including the recent record breaking heatwave here in the UK - not quite Italy but we were 38 degrees outside here in the south-west, which was a record.
From this I can see that it gets hot - but it is still working. It gets hotter when the tub is running (11:00 to 14:00 each day - can also see when it was used or ran twice). The base (minimum) temperature probably mirrors the ambient air temperature, but up by 20-30 degrees or so. I have a solar pv inverter that also reports the internal core component temperature, but the documentation suggests that a reading up to 175 degrees is quite possible, so I don’t think anything up to 100 degrees should worry us at all. Ironically, electronics are more susceptible to issues with wide changes in temperature rather than a consistently high temperature, so I’m not losing any sleep over a mere 75.