Yes, I first added node.js like you suggest:
IMAGE_INSTALL:append = "nodejs"
IMAGE_INSTALL:append = "nodejs-npm"
... but actually, node.js layer alone is enough because npm comes with it, so I am finally keeping this line only:
IMAGE_INSTALL:append = "nodejs"
Yes, Honister supports node.js v14, but imx layers upgrade node.js to v16.
I removed the v16 upgrade to try out node.js v14, but I faced compatibility issues with other components during the build (ex: openssl). I started to fix those compatibility issues one by one, but I gave up because it was never ending. That's when I decided to ask some help on this forum.
In parallel, I've built a complete new image based on Hardknott which supports node.js v12:
repo init -u https://source.codeaurora.org/external/imx/imx-manifest -b imx-linux-hardknott -m imx-5.10.72-2.2.0.xml
... and Node-RED installation (import recipe from meta-iot-cloud) succeeded at my first attempt.
My conclusion is that installation of JS modules with npm, coming with node.js v16, brought by imx images based on Honister, does not work. I don't know exactly where or when this has been broken, but I would recommend images based on Hardknott.
(by the way, I think I posted this question in wrong forum section, I should have posted it in Software Forums, sorry about that)