Helo Sam,
creating two same topics in two different sections does not make too much sense. Especially because when a target is supported in MbdOS then is also usually supported in any Mbed tool.
According to these two topics (please see links below) it seems the board was supported in MbedOS 5.15, but later NXP decided not migrate this board to MbedOS6 and source files were officialy removed in MbedOS 6.6
- LPC55S69 support in Mbed OS 6 - Mbed OS - Arm Mbed OS support forum
- How to use mbed os 6.5 for LPC55S69 - Mbed OS - Arm Mbed OS support forum
About the example. The Mbed allow you to run same code on much different targets so usually is not necessary have a target specific example.
So finally you can do this. Follow this Arm Keil Studio Cloud User Guide - Get started with an Mbed OS Blinky example
Just in point two don’t look for MbedOS 6 but for MbedOS 5 in the list, like on picture below.
BR, Jan