Is there an external IO pin on the IG60 Laird Linux I can use for my purposes?

Yes, there is one pin (4) on the power supply connector that can either be configured as an input or output.

The same pin can be connected to the AD converter of the IG60s host processor by software.

Consult Lairds application note "Configuring external I/O pin of the IG60 Laird Linux variant as input or output" to configure pin4 and this tutorial to use the AD converter on the host processor:

https://lairdcp.github.io/guides/60-som-dvk-docs/1.0/ad-converter-tutor…