QSFP 100G transceivers, could they be hacked to be used with PCIe v4 ?

I am toying with an idea of connecting several machines through PCIev4 interface.

There are cables for this kind of stuff ( mainly from Bitcoin etc crowd), but those are short.There are also PCIe bridge cards that communicate through fiber up to couple 100m, but those are hard to get and cost a fortune.

So i thought about using active QSFP modules, that should be able to transfer 4 pairs bidirectionally.

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QSFP-100 should be good for 2GBit per pair, which should cover PCIe v4 nicely.

So my question is - is there an obstacle that would prevent me from doing so ?

Do these things sample I/O signals and demand that they be properly clocked ( and at the right rate etc) or do they simply transfer signal that they get, possibly in digital form ?

They do have 4 Rx/Tx pairs, so in theory I should be able to transfer PCIe x4...