I’m going to close this. Basically because it is overly specific, but general threads exist for this problem. Reasoning and links below. Thanks for understanding!
There are existing threads and at least these FR for quick add (some are mobile-specific).
I’m not sure about suggesting a MacOS workflow using the dock icon. It seems like an overly specific suggestion for a general problem. The important part of your request seems to be that it is in a separate window, so your other notes don’t necessarily need to be exposed.
I think it would be better to lend your support to the general feature request.
And in the meantime, there are also existing workflows and plugins for quick add.
Here is another thread or two with some ideas. Further search ideas to find more: “capture”, “quickadd”, “jot”, “inbox”.