For anyone bumping into this, server actions were considered by many a boilerplate-free alternative to tRPC, and not being able to execute them in parallel was far from ideal.

There are even a few (12 months old) issues in Next.js repo regarding this, so it's obviously a known pain-point for many people.

Well, it turns out you can actually invoke them in parallel, have a look at the repo here: https://github.com/icflorescu/next-server-actions-parallel