I am a little confused on the situation in your side, are you using the Yocto in your side?
If yes, here you do not need to use the Stand-alone build, just use the Yocto modidy all the code you need to , when finished compile, it will generate the wic.zst file in the /tmp/deploy/images folder. So you do not need to add uboot and kernel build images and kernel modules to the wic.zst file anymore. It is the easist way to do. This is the first method.
If you already generate and download the wic.zst file to your board, here just compile the u-boot and kernel files, you only need to downlaod the u-boot and kernel to your board, no need to download the wic.zst file again. This the second meathod.
So about your questions:
Additionally, I would like to know how to add uboot and kernel build images and kernel modules to the wic.zst file in the /tmp/deploy/images folder that is the yocto build result.
You do not need to do like this.
Any questions contact me freely.