PCIleech was originally a framework developed for general pentesting and redteaming. Under certain circumstances pcie devices have read and write access to the entirety of the RAM without any special software running on the connected PC. The pcie device can simply send packets requesting the contents of addresses and the bus happily responds.
This enables all kinds of interesting things. Unfortunately games also store the position of enemy players in memory, so people use it to read those values from memory.
But at least we got cheap fpga devices from that situation.
Is that still the case? IOMMUs have been a thing for a very long time, and nowadays you don’t trust random devices anymore. Certainly a Thunderbolt port (which is PCIe-via-string) does not want to expose memory unrestricted, and while you might be tempted to think that a built-in PCIe card could be under more lax policy because it’s considered “physical access”, you don’t actually want the driver code for that card to be a wide open attack surface for the rest of the system.
All of these options can be had for ~100$.