A new alternative to the Raspberry Pi is now available. The Banana Pi BPI-F2P also allows the connection of external devices, but it has a different focus than the popular Raspberry Pi.
https://www.notebookcheck.net/With-PoE-New-Raspberry-Pi-alternative-also-supports-TPM-2-0-RS-232-DB9-and-RS-485.463439.0.html