Set expand_alias when shopt not available?

I'm trying to use an alias in a shell script I'm writing, but it is not working.

The alias:

alias ts="awk '{ print strftime(\"[%Y-%m-%d %H:%M:%S]\"), \$0 }'"

When I run the script, I get the following error:

./copyTask.sh: ts: not found

Sooping around on the internet, it seems that I need to enable the expand_aliases shell option, but I don't have shopt installed... Is there any way I can enable alias expansion without using shopt or creating another rootfs image?

I'm using the ash shell. And awk is BusyBox v1.25.0 awk.

NOTE: The alias is an easy way to prepend a timestamp to a commmand:

$ echo "foo" | ts
[2005-06-23 11:52:32] foo

EDIT: as some people are having trouble understanding what I mean, this answer has an example.

Solution

Don't use aliases in scripts. A function does the same job better.

ts() { gawk '{ print strftime("[%Y-%m-%d %H:%M:%S]"), $0 }' "$@"; }

This works with any POSIX shell, including ones that don't support aliases at all.
This works with noninteractive shells without needing to enable alias support explicitly.
This can be extended in ways that aliases can't (you can put conditional logic inside functions; you can put arguments in non-tail positions in functions; etc).
In bash, functions can be exported to the environment: export -f ts will make the ts command available to subprocesses (where the shell they run is also bash).