Replacement MOSFET (in a different package)
SO8 is rare, but DPAK might work. Infineon, for example, has plenty. The IPD088N06N3 (DPAK=TO-252) with 60.0 V and 8.8 mOhm seems to be closest, but there are many more with even smaller Rds,on. To get a good comparison, I suggest relying rather on Rds,on and not on the current rating, because the latter is used differently by various manufactureres.