Of course. But you have to run RClone in Docker within the DSM and perform a one-way sync:
1. Please install Container Manager from the Package Center.
2. Then select Registry from the left side, search for cenode/cyclone, install, and run it.
3. Tap Image from left, rename the container, enable resource limitation, and auto-restart.
4. In Volume settings, add the folder containing your RClone configuration file, and set up Read/Write. Select the folder on your Synology NAS as the location, and set it to Read-Only.
5. In the Environment Settings, Set pCloud as the target, and Synology NAS as the source, and hit Next.
6. Tick Run this container after the wizard is finished, and hit Done to sync Synology NAS to pCloud with RClone.