Due to how Flatpak sandboxing works, Dolphin only has partial view of the host filesystem and some folders are not accessible at all.
For more details see the Filesystem access section of the Flatpak documentation.
- Accessing sftp (missing libssh dependency and KWallet communication)
- Accessing mtp (missing libmtp)
- Not visible mounted devices (most likely because of no access to plasma dataengines)
- Accessible from /run/media