It is very likely that relay switch is one of:
smali/cloud/shelly/stargate/helpers/DeviceSettings.smali: const-string v0, "/sys/devices/platform/leds/green_enable"
smali/cloud/shelly/stargate/helpers/DeviceSettings.smali: const-string v1, "/sys/devices/platform/leds/red_enable"
You can test that by trying to do
echo 1 > /sys/devices/platform/leds/green_enable
and
echo 1 > /sys/devices/platform/leds/red_enable
respectively. That should enable realy, echo 0 should disable it.