I did the same thing and got the same redirect. I haven't experimented with anything except GET / but it would be interesting to try throwing some params in there and trying other paths.
Yeah, after another week or so to get my initial impressions with the router as-is, I'm going to do some more experiments and also swap out a couple other routers to see what I can do.
Sweet man, would you be interested in teaming up a bit? I'm fairly busy the next couple of weeks but I can find a little time to do some hacking. I'm FreedomBen on Keybase, or if you want to email me freedomben <at> proton mail dot com I can give you a real email address. Totally fine if not though!
It's not the official place where I'm working on this particular project, but if you have any notes or feedback you'd want to track/share through my internet-monitoring project, please feel free! Email is a bit tough, as the volumes right now mean I sometimes see a message quickly, other times after days or weeks :)