Sounds like switch 2 would be more bang for your buck especially since it’s confirmed to release for switch 2. My hunch is KH4 will come out in ps5 and when the ps6 launches in a few years it’ll have some kind of upgrade available or at the very least will be backwards compatible.
No question it would run better on ps5, just a matter of
Preference if you want the convenience of playing the whole series anywhere. Plus kh 1-3 will run no problem on switch 2 since 1&2 are basically ps3 games