I was wondering if the gateway is capable of handling any sensors connected to it.
It's not recommended. Let the gateway handle radio<->serial communication to minimize missed messages.
Locally attached sensors on Raspberry PI Gateway
Sensors on Gateway?
not working Ethernet Gateway (sensebender and/or nano gateway)
Pir AS 312 with 2 rechargeable AAA battery. Boost needed?
In line humidity sensor
Open Smart serial TFT LCD touch screen - example Arduino code
HMI Intelligent TFT screen - control via serial, $4