Found this a very nice play. Partly because at first I was a bit clueless and had to gradually find my way.
In the meantime - being clueless - I decided to use negadocter i.c.w. (un)masked composite. Both new modules to me. Fun though the results are not special.
I use darktable and I’m also learning Resolve. To me, the main difference (besides the interface) is that darktable has a defined default sequence of operations (modules) called the pixelpipe. Color editing in Resolve can be more freeform, which is powerful, but challenging for beginners.
In darktable, it is common to use more than one instance of certain modules. A simple example is to use the exposure module to set overall exposure, with another instance on top with a mask to make a vignette (akin to a stationary power window). So it is a little bit like adding a node to your tree in Resolve, except that Resolve nodes can take any function, whereas darktable modules are more specialized.
Darktable modules stack from the bottom up.
I think that once you learn the interface and a few key modules, your experience with Resolve will help you to become proficient with darktable.