Depending on your jurisdiction and applicable laws, you are responsible and accountable for the traffic that goes through your internet connection. Anything happens, and the authorities will ask your ISP through whose connection was an illegal activity initiated, and they’ll point their fingers to you as contract holder. If it’s a family member or a visiting guest, you can figure out who caused the issue and confront them or show some evidences out of your own router; but if you allow any unnamed individual to use your internet connection in a way that you can never ever trace them, you’re just exposing yourself to a significant risk without any benefit. Why would you do that?
If your Proxmox box has an Intel CPU with AMT, like the vPro series of CPUs, that’s basically a built-in BMC without a dedicated network interface. Once you configure it with the like of MeshCentral, you can remotely manage the Proxmox box, including full display replication.