For a consumer/household: This is almost entirely unnecessary. Basically any halfway competent name brand router/firewall will have no problems with this. You are more likely to see issues coming from your wifi network (which is probably part of your “router”), but that is also an incredibly situational one depending on your environment (how many neighbors, etc). But LAN->WAN NAT is a “solved problem” as it were and you mostly just want to stress test that speed wise.
For enterprise/hotels? Yeah, that is when you are going to have issues with too many clients. And the answer to that is almost always “buy enterprise hardware” rather than “figure out which netgear router I can tape to the ceiling”
More data is always fun (unless you are the one collecting it…) but I just don’t see much benefit from this. And most of the suggestions in this thread are really just ISP tests.