There is no reason parallel start would be problematic; I even got stuff working that needed network access to get creds for encrypted partition that was required for database to start and it was handled flawlessly.

More than that, if for some reason that file system wasn't mounted it would be when I told systemd to start database, it would run the service retrieving the secrets, then the mount using it, then the DB.

The worse story is with shutdown; by default most distros will cut ssh access before services are closed so if some of them hang you can't debug that remotely. But that's mostly bad settings rather than bad design of the daemon