Would it be possible to put a pcie switch on a carrier board?

I am trying to make a custom board design for my project and I would like to use the input/output capabilities of the module to their full extent.
From what I can find, the 1x pcie gen3 should be capable of around 985 MB/s, and the 4x pcie gen4 around 1.97 GB/s per lane. Right now the highest throughput device I have is an nvme module capable of 3.5 GB/s. If I used a pcie splitter could I connect the nvme module and another device to the same pcie 4x interface to make use of the extra 2GB/s capacity?

On Xavier NX, it is 16Gbps per lane for gen4. You can get the info in Product Design Guide.