AAPT2 failing to merge resources on Docker
I stumble upon the same error. The problem as you suspected is that Alpine Linux ships with Musl instead of GNU libc, the Android SDK tooling requires glibc.
You could use something like this: https://github.com/frol/docker-alpine-glibc, or create a similar image on your own if you're comfortable with someone else compiling glibc for you.