Hi,
Why don’t you use the input 3V3 pin as power input with a lifepo 3.2V battery?
Soldering a battery is in my opinion not a good thing with these pads. It’s stronger to use the pins.
Of course if you do this, 5V pin won’t be powered.
All your devices will be powered with the lifepo, so no current limitation (other then the battery one).
For flashing three ways:
1 - using native usb with pins IO18 (D-) and IO19 (D+). USB connector is useless in this case
2 - using the USB connector but in this case pin 3V3 must be disconnected during flashing.
3 - using TX and RX pins and an external UART adapter connected to your PC. In this case remember to connect only GND, not VCC to the ESP32-C3.
It’s as simple as this!