Anything important should be kept inside the file. Filesystem metadata gets lost all the time, isn't consistent between operating systems, zipping up a folder and extracting it will probably mess up timestampts too.
Something related: exporting originals from Photos used to give the current timestamp back in Ventura, which annoyed me to no end.
They fixed that bug in either Sonoma or Sequoia (I jumped straight from Ventura to Sequoia).
Dropbox doesn't seem to keep timestamps properly either.
I like using filesystem timestamps to sort through things in Finder, and thankfully I like A Better Finder Attributes for being able to batch copy EXIF data into timestamps.
[1] https://www.publicspace.net/ABetterFinderAttributes/index.ht...
Sorry, I'm not sure if I'm missing something, but what's rsync's role in this?