Control active ambiences using a tristate "notification" slider under SFOS.

Chosen ambiences are controlled via dconf @ /apps/onyxtristate/:

[apps/onyxtristate]
top='silent'
middle='sailing'
bottom='origami'

There is also a Sailfish OS settings plugin available for simple control of these values through the settings app.

You can now add a /etc/dconf/db/vendor.d/triambience-daemon.txt file in your droid-config sparse files to choose the correct tristate key node and emitted key event codes if needed without having to fork this project, for example:

[apps/onyxtristate]
sliderDevice='/dev/input/event6'
sliderCodes=[0x25b, 0x25a, 0x259]

To find the device event node you can install the mce-tools package and run evdev_trace; it should be pretty obvious looking at the names which one is your device's tri-state key / notification slider:

[nemo@OnePlus5 ~]$ evdev_trace
...
----====( /dev/input/event3 )====----
Name: "tri-state-key"
ID: bus 0x0, vendor, 0x0, product 0x0, version 0x0
Type 0x00 (EV_SYN)
Type 0x01 (EV_KEY)
	 KEY_0258 KEY_0259 KEY_025a KEY_025b
...

In this case /dev/input/event3 is the device node and you can define it as the sliderDevice dconf item value and use the number at the end of the device node in the command below.

Now move the tri-state key to it's middle position, run the command below and go through all the positions going top-to-bottom:

[nemo@OnePlus5 ~]$ evdev_trace -t 3 | grep '1$'
/dev/input/event3: 1587214927.004 - 0x01/EV_KEY - 0x259/KEY_0259 - 1
/dev/input/event3: 1587214928.329 - 0x01/EV_KEY - 0x25a/KEY_025a - 1
/dev/input/event3: 1587214929.648 - 0x01/EV_KEY - 0x25b/KEY_025b - 1

From this example output we can determine that the key top position yields code 0x259, middle 0x25a and bottom 0x25b, which you can place all in the same order as the sliderCodes dconf item value.