Kind of? But kind of not? When you stake with 1750PRV, you can always get those back, in addition to rewards. But when you buy a pNode, that $400 isn’t 450PRV you can get back.
So I’m with @aaron that split staking isn’t the right phrase. But I think funded staking isn’t the clearest option.
If pNodes are part of powering the DAO, then having pNodes automatically switch off of funded staking at some point isn’t something they are likely to support.