GitHub Actions Expressions would benefit from jq-like syntax

[giner]

The Expressions are currently limited to a small set of operations. This results in people writing actions to do such a simple thing as splitting strings:

• https://github.com/marketplace/actions/split-action
• https://github.com/marketplace/actions/split-by
• https://github.com/marketplace/actions/simple-split
• https://github.com/orgs/community/discussions/26625
• https://github.com/orgs/community/discussions/25768

Which does not only make workflows heavy but also makes it impossible to use these expressions at the pre-processing step before any job runs. How about adding flexible and time-proven jq-like language to the Expressions?