Power factor controller selection
Flybacks need Common Mode line filters to pass EMI specs.
Active PFC don’t use less power, just less reactive power to the point current matches voltage wave so it appears to have high PF .
Power supplies &lt; 100W do not “need” PFC only &gt;= 100W .
Stepping up the voltage reduces the current demand on a buck components.
TI’s designer for PSU’s will assist you with your spec requirements and their solutions for complete designs and simulations. Analog Devices , ADC as well.