Memfault is enabled by default in all standard firmware builds. Once a device is provisioned to nRF Cloud, it automatically forwards coredumps, LTE and location metrics, and other diagnostic data to the Memfault project linked to your account through nRF Cloud CoAP.
For deeper post-mortem analysis, you can also capture modem traces around application crashes and upload them to Memfault. Use the pre-built -debug-thingy91x release artifact, or apply the modem trace overlay when building locally, as described in Use Memfault.
Remote debugging enables the device to send metrics such as LTE, location, and memory statistics, as well as coredump captures on crashes, so you can analyze problems across single devices or a fleet of devices once they occur.