the MOSFETs are only needed for analog LED strips.
Basically you need to trace the PCB wired from the MOSFETs to the chip.
The one PIN is connected to a cable towards the strip - this is “OUT”.
Another PIN is connected to ground.
And the last PIN is the one you are looking for - this will end on one pin of the chip.
You need to desolder both chips (either with a rework station with hot air or with a lot of solder on all pins of the chip and the use tweezers to grab the chip).
Please be carefull - the PCB wires must be okay after that - you need to solder the INPUT there).
…then - if all chips removed, solder wires to the 4 input PINs (on the places where the chipsn have been).
…the other end of wires should be directly connected to the ESP PINs.