Hi Varun, welcome to the forum.
I'm not familiar with boards that have 4g built in I'm afraid as I don't have that need but I expect they exist. Otherwise, there will be addons for many other boards.
I'd say that the absolute minimum general spec you need for running Node-RED in general will be something like:
- At least as powerful as a Pi Zero or 1st gen Pi - however, they are slow to compile some dependencies.
- At least 512MiB of memory. You could probably get away with 256MiB as well but may get issues with larger implementations of Node-RED even for home use.
- Running a reasonably standard form of Linux (something based on Debian is easiest since Dave's install script is likely to work)
- A few GiB of storage - the format doesn't really matter that much unless you need the performance. Even the standard Pi SD-Card type is sufficient for most uses.
I ran Node-RED off a 1st gen Pi with that spec for quite a while. For the longest time, my main device has been a Pi2. That works very well and is completely stable - but, bear in mind that I just use it for Home Automation. Even so, it runs NR, Mosquitto, InfluxDB, Telegraf and Grafana. I started to move to a Pi3 which, with its additional memory, is capable of running the above plus the Java-based Wi-Fi controller for my Unifi AP's.
Without knowing more about what you are trying to do with your board, it would be impossible to say much more really.
Of course, assuming you want to start adding other services, you will start to feel the