Hello,
Thank you for contacting NXP support.
Yes is possible to use UART to flash the firmware a tool that can be used for this can be the Secure Provisioning Tool.
And regarding the Serial Wire Debug, you can use this also to flash the firmware is not strictly necessary to debug to use this feature.
Information related to SWD can be found on the Reference Manual Chapter 21.2.1 Serial Wire Debug. And also more details on the following application note.
Please let me know if there is anything else where I can help you.
