Joplin's own sync service [1] works seamlessly for me. The basic plan is enough for my needs and is way cheaper than obsidian's sync subscription.
But you can't open joplin, create a note, and then immediately exit and expect the note to show up on other devices. It will still exist on the device it was created on, so it's not lost, it just hasn't synced yet. It will automatically sync the next time you start joplin though.
In my case, I use the vim key bindings, and am so accustomed to hitting "<esc>:w" (which does perform a sync) when I'm finished writing the note, I never noticed.