You should check out the local copies feature: darktable 3.8 user manual - local copies
If you can handle a bit more technical complexity, check out git-annex, which fits this type of use case perfectly. There is even a lua script to help integrate it into darktable. Using git-annex would allow you to import files to your laptop, check them into gitamnex, then transfer the files to your NAS when you get home. Then drop the files from your laptop when you’re ready.