> place 2 diodes in series per each branch, and obtain 3.6V

Dario, can you guarantee the voltage drop across the diodes as the
load varies won't affect the circuit ? For example,

1N4001 0.7V @ 10mA, 0.75 @ 100mA, 0.9V @ 1A
BAT46 0.25V @ 1mA, 0.4V @ 10mA, 0.75V @ 100mA

diode-ORing them followed by an LDO 3.3V regulator perhaps

wbr
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