@Jake Lo @Hervé
Hi, good news! i got the touchpad working without any weird behaviours and discriminations.
i used the VoodoooPS2Controller version found on my first post from github, which did the magic.
i will attach it here should someone too facing similar problem on big sur could also try it.
Here is my touchpad info when i used linux to check maybe it could help.
I: Bus=0011 Vendor=0002 Product=0008 Version=0310
N: Name="AlpsPS/2 ALPS DualPoint TouchPad"
P: Phys=isa0060/serio1/input0
S: Sysfs=/devices/platform/i8042/serio1/input/input6
U: Uniq=
H: Handlers=mouse2 event9
B: PROP=9
B: EV=b
B: KEY=e420 70000 0 0 0 0
B: ABS=260800001000003
E6430_Big_Sur_VoodooPS2Controller.kext.zip