Raspberry Pi Pico (RP2040) based board with integrated RTC and SD Card reader.
Challenger RP2040 MSTK from Invector Labs on Tindie
arduino-pico/README.md at master · earlephilhower/arduino-pico
Challenger RP2040 SD/RTC from Invector Labs on Tindie
Downloads
Challenger RP2040 SD/RTC - iLabs Electronics
Challenger RP2040 WiFi from Invector Labs on Tindie
iLabs Challenger RP2040 SD/RTC – Elektor
Challenger RP2040 Wi-Fi: A better Raspberry Pi Pico W than the
MCP79410 Archives
Challenger RP2040 SD/RTC - Feather-Compatible RP2040-Based