I have use variuos usb devcie (cdc/hid/msc) with various stm32f4 but always via CubeMX and always worked almost of the box
So it”s worth ginving iy a try.
iti s quite easy to miss one init and break everything by copy pastign only part of exmaple it is wize to use the exampel as start point
What about clok ? Are your sure about your 48MHz? if that clcok is wrong usb will not work.
Do you have usb ip clk enable ?
do you have the all the PCD and USB LL file right ?
Not that “fs id” is needed only if you want to suport “otg”, the minimal requirement for devcie only (self pwoered) is DP/DM all other are optional.
if the base usb is ok at least you should get a first Irq (on cable plug ) after that much more need to happen to compelte the enumeration .
Yes usb code from L4689 eval shalll work on dsicovery (same mcu)
note that debuging usb emueration and transsfer comonly lead to enumeration or xfer failure due to short time out on the host side but its still help udedrtanding how things going on device.