Another 'search random landmarks for thing x, until you have enough data for a nav point.' In this case, the landmarks are minor Remnant outcroppings, and thing x is a Kett listening device.
This can be found in Remnant ruins, but mostly smaller ones (ie not monolith sites or vaults). Keep an eye out for the small outcroppings with entwining vines. Actual placement seems to be random, but I had the most consistent luck checking ruins in the northmost sections of the map. You need to find five of these devices to trigger the next step. When you destroy the last, SAM will feed you the navpoint.
This leads to a hidden minivault in the northwest.
Enter the facility and descend the well to be ambushed by Kett.
Kill them, and use the Kett console on the high platform to learn their plan.
Proceed forward into the vault, killing Kett as you go. Your radar will have four navpoints, each a device to be destroyed.
The main section of this map is shaped like a figure eight, so there are a number of ways to clear it, but if you bear east from the main junction, you'll wind up in a room with one of the devices, and a Remnant Data core.
This same room has a high-value container, spinny core, and a Remnant Cache in the middle. You'll need two glyphs to open it, and they're on opposite walls- one south, one north.
The puzzle itself is one of the kinder ones (start with the bottom row).
Continue to make your way around the eight, killing Kett and popping their devices.
Take out all four for a Viability reward, and an end to the mission.