Interesting tutorial on how to use Joplin with Syncthing:
I like the idea and use syncthing for my documents folder across devices. Unfortunately syncthing doesn’t have an iOS app.
I’m also hesitant to expose too many services to the internet from my home network.
Also, doesn’t Joplin encrypt the DB and attachments it stores (in Dropbox in my case)?
Don't sync your joplin home directory. This can lead to a corrupt database. As you have also noticed the data there are all not encrypted. Use file sync and sync this folder with syncthing. As it is described in the article.