I bought the iFixit Manta Precision Bit Set some years ago. So far I haven’t found a screw it doesn’t work with. If you regularly open old devices, there are some truly esoteric bits in there
As these screws are fairly small you will need a high quality PH00 screwdriver anyway.
I don’t think those are easier to find than a comparable torx one…
I have an idea why they do not take Torx screws (without knowing if that is really the reason).
The good thing about Torx screws is also the bad thing about them: it is possible to carry very high torques. If someone is not very careful, the seat of the screw could be damaged. PH00, on the other hand, has a built-in slip clutch, so to speak, which protects against over-tightening torques.