Well, I figured it out myself.
The reason I could't see anything even when port-forwarding to a pod was because the dashboard was forbidden from accepting insecure connections. I would've prefered to get a 403 response instead to point me in the direction of my error more quickly, but at least I now understand why it wasn't working.
I was also unable to access the dashboard through a ingressRoute with or without TLS. Turns out my mistake here was that I'd attached the IngressRoute to the traefik entryPoint, while I should've attached it to the websecure entryPoint through which my TLS encrypted external traffic was coming. Changing the entrypoint made the dashboard work right away even with insecure set to false (since the traffic is now coming through a secure connection)