Why make it when you can buy it?
- TP4056, can be directly connected to solar charger
- 3V3/1A created by 3 parallel LDO (77µA total quiescent current)
- 5V/1.7A boost converter (260µA quiescent current). There's no way to turn the boost converter off.
- Not suitable to charge and discharge simultaneously.
- Quite big
This one from AliExpress has only a 5V booster.
How much current is needed?
The original idea was to build a 3V3/2A supply. But is that a good idea? How many battery powered applications need a regulated 3V3 at 2A? Sure we can build it, but it will be running at much lower currents for most of the times. The efficiency at lower currents will be much lower. The cost will be higher because of the bigger inductor and more expensive switcher.
1A will be enough for most applications, including the #easy-alarm-clock for which it has originally been designed.