I've uzed the original mbed NXP LPC1768 several years ago, and didn't do too much with the vendor ecosystem, but it was very easy to just use the regular ARM-GC

I've uzed the original mbed NXP LPC1768 several years ago, and didn't do too much with the vendor ecosystem, but it was very easy to just use the regular ARM-GCC compiler and extract the functionality I needed from their libraries into my own projects.