Include:AbuildRootBld
Install package abuild-rootbld:
apk add abuild-rootbld
You may now build your packages from source in an unprivileged sandbox based on bubblewrap with the command:
abuild rootbld
rootbld assumes your APKBUILD file is in a directory structure like aports or you need to set environment variable APORTSDIR to current directory.
If the build process needs network access there has to bet set the net option in APKBUILD.
Note that using rootbld inside a docker container requires additional configuration.