Copper: great question:
If the project is a one off, personal use or for lab, the 0.65 PF of a classic FW rect><bus lytic is fine.
In general adding the PFC reduces efficiency, increases size and cost.
See the IEC, CISPR and other stds on PF classes, exceptions, and requirements in EU, similar power quality regs exist in UK, USA.
Finally a PFC is required for commercial products esp if shipped out of your country.
A dedicated PFC module is unusual, and at multi KW power I have not seen.
Boost PFC is very easy to build, boost switch, inductor, bus cap, control IC.
it is usually included in the main SMPS as front end.
Bon chance
Jon