create entry-point script to get all env variables starting with VUE_APP_ and take it's value
While it's not clear what your trying to do (the script you have so far for the bit you are having trouble with would probably be handy), I think you are essentially just trying to parse your environment and manipulate the variables at the start of your script?

I don't see why add something like this to the first line of your script wouldn't work:

eval $(typeset -p | grep -E 'declare -x VUE_APP_' | sed -e 's#declare -x VUE_APP_#export VUE_APP_#g')


But then I also don't know what shell you're running or anything else about the container, so I'm not sure..