Copperhill’s third-gen, $65 “PiCAN3” HAT features Raspberry Pi 4 support and a SocketCAN-ready CAN-Bus 2.0B port. The HAT has an RTC and is powered by a 3A, 6-20V Switch Mode Power Supply that can also power the Pi.
Source: CAN-Bus HAT for Raspberry Pi 4 offers RTC and wide-range power