I use an rsync job to do it. Rsync by default uses the files metadata to determine if the file has changed or not and updates based on that. You can opt to use checksums instead if you’d rather. IIRC, you can do it with a Synology task, or just do it yourself on the command line. Ive got a Jenkins setup to run it so i can gather the logs and not have to remember the command all the time (and i use it for other periodic jobs as well), but its pretty straightforward on its own.

I’ve heard lots of good things about Ghost. I’ve also hosted Grav for a while and it’s pretty solid. You can do Wordpress, but I’d stay away as it gets bad fast and there are better alternatives. If you needed even more scale, Mediawiki is selfhostable too.