The ESP32 C3 Nano is an Arduino Nano compatible development board, designed to provide enhanced computing power, wireless connectivity, addressable LED capabilities, and a built-in programming and debugging interface. It is based on the ESP32 C3 chip, which provides improved processing capabilities, increased memory, and wireless connectivity compared to traditional Atmega variant. The board maintains compatibility with the Arduino Nano form factor, ensuring easy integration into existing projects and making it a drop-in replacement for the traditional Arduino Nano board.
If you can scale your passive, it would save you a lot of space like 0402 or 0201. JLCPCB should have those in standard part. Buck might be big but a high voltage LDO is easy to find.
please add lipo, solar panel, aa 1.5 v 18650 3.7 steper updown 1-25V