This concept of user vs debug builds is there in Android and any
Android developer who gets introduced to yocto may look for these
options. There seem to be many implementation choices here, trying to
summarize some of the options here.

1. use different image recipes example-image-user.bb vs
example-image-debug.bb but this still poses a problem for kernel
recipes as kernel needs to have different config fragments or
different defconfig for debug vs user variants. One possible option is
to use KTYPE to select tiny vs standard or define own for custom BSP
layers. What about other recipes like u-boot or firmware for other
remote processors, how to percolate the debug vs user options to those
recipes via just an image recipe ?
2. use different configs using multiconfig. Base config (which is
debug) also selects the user config hence always building both build
variants in different tmp directories. Kernel, remote firmware and
image recipes use variables from the multiconfig cof files to decide
whether to build debug or user variants.
3. use different distros. DSITRO=user bitbake example-image,
DISTRO=debug example-image. Kernel and remote firmware recipes use
variables from the distro to decide whether to build debug or user
variants.

Which is the best method ?
All these options seem very BSP layer specific, is there something
more generic and better than the above options ?
If not, should this be a feature request to the Yocto project ?

NOTE: debug variants may include the following.
- more debug related kernel configs and security loosened and UART
ports disabled
- image recipe debug variant may include debug utilities absent from
the user variant

There could be more than just debug and user variants. Android has
engineering, tests, user, tiny and user-debug.

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Regards,
Karthik Poduval