Hi Peter,
I am new to this too, but I have done something similar.
In general terms what you want to do is defiantly possible.
By that I mean there are products on the market that have the functionality you are after.
However it may not be feasible given your budget and requirements.
Eg the apple watch does those things and more. you can by one for a few 100 euro but if your were to make one from scratch…
2G is going away slowly, I am not familiar with its status in Italy. It also is heavy on power which would be my reason for not using it.
The Pycom FiPy supports CAT M1 and NBIoT it also support LoRa, Sigfox which maybe more appropriate for your project given the small amount of data you are transfering.
It is my understanding that the dash is dead. We spent a fair amount of time and resources developing a trial based on it. We went to buy 50 for a broader trial and discovered they were discontinued…
We moved to the pycom boards mostly for power consumption. The deepsleep is reasonably good (the dash was not particularly good on power)
I have no experience with the Adafruit Fona 808
If it were my project I would go with FiPy and PyTrack (the other pycom dev boards are cheeper but lock you into a communication protocol where the FiPy gives you the flexibility to experiment with all of them. )
I don’t use GPS much. My projects are monitoring equipment that is generally fixed to the ground but disconnected from power for several months before it is moved. GPS would be nice to have but it draws to much power.
DIY size is limited by convenience taking the Pycom example. The FiPy+Pytrack+aerials and a battery. should comfortably be less than 2 decks of cards.
You have a bunch of extra features and connectors that you don’t need but you didnt have to make your own board. If you wanted you could buy an OEM module from pycom and the components you need from the pytrack, design a board and go from there maybe get the size down to a match box or slightly bigger depending on the battery. (30 second cloud updates and gps reads is going to drain the battery, it may still be bigger than a deck of cards)
the lower limit for sure would be bigger than this KROAK Mini GPS Tracker Positioner Module GPS+AGPS+LBS Multiple Locator SOS Alarm Sale - Banggood USA sold out-arrival notice-arrival notice?
Best of luck
Dane