In your opinion, regardless I have to set those systems up anyways to use the Earthly system. Jenkins caches by default and has parallel(), actions uses actions/cache, actions is also async so it's parallel by default. Both can use docker and take advantage of dockers caching management and make is a great tool, but again, any build system can use make.

I don't think it's harder at all, in fact in my mind Earthly is more money, more steps, more time and energy, and more vendor lock in for the same output you can get in just about any modern build system.