Firstly, how are you going to power your device? If you have a modern radio, or even a cigarette lighter USB adapter, then you can easily power an EDSP32, Raspberry Pi Zero W, BBC:Microbit, Arduino, etc. All of those could get the job done – with, in some cases, additionally Hat/Shields, so choose one that you are familiar with.
I need to determine when a van leaves or enters a geofence range, and alert a system on my side - either via an API call or email sent - so that I can digest that data for later. My blocker is finding such a device that will work with my requirements.
I am not sure if you need to know in real-time that the van left the geofence, or just that it happened. If the latter, then you could just simplify things incredibly by writing to SD card and interrogating that later (making sure that the drive cannot interfere with the data).
My goal is to be able to set a trigger of leaving/entering the geofence, and via internet connection that the device emits it will ping an API endpoint that I will build. The API endpoint will accept a POST of all data that the device can send to me. From there my API will update a database for additional logic.
If you could guarantee free WiFi coverage everywhere that the van goes (possible in places like Singapore), then the ESP32 & Raspberry Pi Zero W are ideal, as they have built in WiFi. You might also consider BlueTooth communication to a ‘phone and use its data plan, but then you have to create a ‘phone app.
Probably the simplest way is to use GSM. The Orange Pi 2g IoT and 4g IoT are prime candidates as they have integrated SIM car compatibility. They come with a Hologram SIM card – check here for pricing. They are very cheap, no monthly fee, pay only for data sent and over 196 countries across 550 carriers. See also my personal choice, at the end of this answer.
Alternatively, look for a 2g or 4g Hat/Shield for your board of choice.
If pinging an API isn't possible, I could settle for an email being sent with this POST data, and my API could scrap that email for the data that I need.
I would think that if you can send email, then you can access an API.
I am seeking advise on if you know a device that would meet this criteria. I am sinking tons of hours reviewing devices, their manuals, calling sales reps, etc. I am reaching out to a member of the IoT community to help me find such a device.
Well, my personal preference is ESP32 (I think that I do not need the Linux of Raspberry / Orange Pi), So I would use a Lilygo TTGO T-Call.
Here is a tutorial, including code, on how to use it to publish data to the cloud.
But, if you are already proficient with Raspberry/Orange/Banana Pi, BBC Micro:bit, Arduino or anything else, you may prefer to use that.